Right, ladies and gentlemen. Good evening. My name is Doctor Mark Hedberg, and I am pleased to welcome you to the Webinar vets Evening session on oral tumours.
Does the diagnosis really matter? We're very glad to welcome Owen Davies. He's an R CV S American and European specialist in veterinary oncology.
Before his residency, he spent almost 10 years in general practise undertaking large and small animal work both in the UK and in India. Owen currently works at Bristol Vet specialists in Bristol and Owen. Thank you very much.
Over to you. Great. Thank you, Mark.
Thanks for the lovely introduction and thank you to the Webinar vet team for having me back on the platform. Just like to start with a shout out to everyone who was on call last night and everyone with small Children because I, too, have only had four hours sleep anyway, on with the show. This is a great topic, really.
I like talking about oral tumours. And the reasons will become clear. This is me.
This is where I work around the red dots here in Bristol, a Bristol vet specialist for the UK people who haven't heard of us. We used to be called High Croft referrals. And now we're in a new shining hospital on the other side of the city.
If you are passing and you're interested, you're very welcome to visit. We love having visitors with prior appointment. So I think oral tumours are, a good topic to learn, for the first reason.
But there's not many of them in a dog. The most common one is the melanoma, followed by the squamous cell carcinoma, followed by the fibrosarcoma and then the acanthoma ameloblastoma. And if you know these four, you you kinda know all of them all that you'll see in 95% of the cases.
In small animal practise, you do have others that counts constitute a few percent between one and 10%. Really. The osteosarcoma and round cell tumours like plasma cell tumour or lymphoma or histiocyte sarcoma occasionally occur in the mouth, but the top four will be the vast majority.
And in cats, the list is even shorter. Most will be this. This is the squamous cell carcinoma, and as a teaser, it's a horrific tumour to deal with.
Second to that, you'll get the fibrosarcoma, and occasionally you can get other sarcomas or unclassified sarcomas like osteo SAR in the feline mouth. But there's even fewer. So what we're gonna do today is we're gonna go through these common tumours and you'll find that it's not a lot of information.
We'll give you a lot more confidence in dealing with them. The other good thing about oral tumours is that the approach to them is often quite stereotyped and doing the same kind of routine of tests and investigations in almost every case. So a little bit of learning can get you a lot more confident in dealing with almost all of these.
So onwards with the show. Let's talk about when these tumours present often when an oral tumour presents. It's kind of obvious, isn't it?
The owner noticed a mouse in the dog's mouth. They may have noticed Dysphagia ale Tosis pain. When the mouth opens or chewing food, they may have noticed bloody saliva.
On occasions you can see other things and don't be Don't Don't you know, Don't be regretful. If you miss these on the first occasion, just make sure you you don't miss them. On the second occasion the tumours that are quite cordially in the now You may not have any of these signs, but you may have things like exo almos.
OK, so when you're dealing with a putative oral problem, don't be afraid of trying to gently retro pulse those eyes. It can be a very useful thing to do or look down, from the from the top of the dog's head to see if 11 eye is slightly rostral to the other again. Some oral tumours will present a cervical lymph omega, and the owner may come in.
And have you noticed a mass just behind the jaw at the top of the dog's neck again? For these, please remember to look in the mouth. If you pick up a cervical mass like that, and for some of the dorsal and caudal ones, you may get a cough or a wretch or a reverse sneeze.
Once you've ascertained you've got an oral tumour, then my investigations typically fall into four categories. The first one is to examine the dog thoroughly and to do whatever tests you think are prudent to anaesthetize the dog for further investigations. Then I would take an FN a of the lymph nodes, remembering that 60% of metastatic cases from lateralized lesions will have contralateral metastasis.
How frustrating is that? Oh, they'll image the jaw and the tumour to plan therapy, and then I'll image other parts of the animal to assess the metastasis. And finally, I'll take a biopsy of the mass.
I'll just give you some more comments on these. So first of all, we're talking about physical exam plus minus heme, biochemistry, urinalysis and BP. Just satisfy yourself.
If you haven't got any concurrent and obvious disease that will affect anaesthesia or surgery. And you know what tests you need to do for these. OK, but please remember to take photos and save them to the animal's file, measure the lesion using callipers and record the extent on the file.
Also mark this on a dental chart. What teeth? What specific numbers of teeth are affected and what aren't.
How close is the tumour to these teeth? What is the distance between the leading edge of the tumour and the tooth et cetera? And this all goes into form in the WHO stage, and it can be tremendously prognostic.
This is a simplified version of the WH State WHO stage of the tumour and you'll see that you can get from stage one to stage three by size alone. OK, the tumour doesn't have to spread to get from stage one to stage three. Yet this is tremendously prognostic.
And the fantastic thing about measuring the tumour like this is that it's giving you really useful prognostic information for free. You don't need fancy equipment and you don't need lots of money when you image the tumour. I think this is 11 case.
One case that actually of many cases where CT tends to win CT will show you far more osteolysis than radiographs. Will radiographs only detect osteolysis when at least 40% of the bone cortex is destroyed. CT will show you much more subtle osteolysis.
And if you think about it, the ramifications of missing osteolysis could mean a very misguided underdose of surgery, and a totally unnecessary, unnecessary procedure before the animal has to have a second revision. So the, the ramifications of missing osteolysis and involvement of the bone is huge. Also, we find that oral tumours may grow into a bone and then decide to grow in one way or the other.
And this CT video here, if it plays, will hopefully illustrate that in watching the video. Please compare this mandible to that mandible and it should become obvious. You see the tumour here far before the mass occurs?
OK, this is the tumour compared to that. So as you look at it in the mandible that appears on the right, you will have a much denser tissue compared to the mandible that appears on the left, right the way to the front of the jaw. Can you see that this is this.
If you were to go just on the gross appearance or the where the obvious mass is, you'd leave an awful lot of tumour behind in sit tube without knowing it seems to grow right to the mandibular synthesis down the medullary canal. Also, imaging the tuna can be useful to make sure you don't get caught out. This dog was referred to me with an oral squamous cell carcinoma and you can see this oral squamous cell carcinoma here.
It's quite high in the ginger her which is a bit weird, but it's not out of the realm of possibility. There were no other clinical signs, suggesting a disease anywhere else than a dog's mouth. But when we imaged it, this isn't a mandibular scream at all.
Sorry, an axillary scream. This is a nasal screen and you see it here in the picture, on the bottom left. It just happens to be eating through the bone into the mouth.
So the treatment isn't surgery. The treatment is radiation, and the prognosis, of course, is very different. So it's worth investing in your imaging of the tumour.
And if that means getting an outpatient CT done somewhere, that can be highly worth it. What we're trying to see with this accurate imaging technology is an aggressive bone lesion associated with the tumour. And the same principles are used to identify this aggressive bone lesion in an oral mass that's invading a bone as it would be in a appendicular roste of sarcoma.
And I'm just gonna go through these three, the three things we need to look for now. Well, the first one is bone lyss. We all know that, don't we?
We're interested in cortical destruction as much more important than medullary destruction. We're interested in perm or moth eaten lysis much more than geographic lysis. This is geographic lysis where, as it might imply, you've got a very well demarcated area of lysis in the bone, and that's not necessarily a malignant feature.
You often see that with bone cysts. For example, this is permeated lysis, where you have lots of holes through the bone, and this at the bottom is mothy and lysis, where the permeated lysis holes have coalesced to form lots of irregular lens of varying depth and varying size. You see that down here?
Secondly, you need to look at periosteal reaction. Have we got an active or irregular periosteal reaction or a smooth perio or periosteal reaction? The active or irregular periosteal reaction is like this, like the sunburst pattern here, and that's the feature associated with malignancy.
The smooth periosteal reaction is much more likely to be a benign finding, and finally, you've got transition zone. A, tumour or an aggressive bone lesion will typically have a very long transition zone that is a large area over which the tumour kind emerges into the nearby tissue, and a benign structure is more likely to have a very clear transition zone, where the boundary between tumour and normal tissue is clearly demarcated. So that's a quick revision over what we're looking for, when we image the mandible or maxilla associated with an oral tumour.
Remember that there's no one feature where the presence of will indicate malignancy, and the absence of will mean that there's no possibility of malignancy. It's a subjective judgement call, and you have to take these factors that I just mentioned into account. So after imaging the mouth itself, I will then image for metastasis.
And in most cases I'll image the abdomen, and sometimes the neck as well. In cases of melanoma or very metastatic tumours, I also image the abdomen now for imaging the thorax. I think three view thoracic radiographs are fine.
OK, I would like them to be very carefully positioned, and I'd like them to be inflated, and I will insist that we have a left lateral, a right lateral and a VD. But if you've done good quality thoracic radiographs, that's often fine by me. Bear in mind that High-quality radiography will find lesions of about six millimetres plus, and if you have got the possibility of doing AC T the CT still wins.
You look at the CT shots in the bottom, right? Radiography is gonna show this lesion, but it's gonna miss those lesions. So CT is definitely more accurate.
But the information on which the prognosis of oral tumours is determined is often based on plain radiographs. Because these papers are, you know, getting on now. They're like 2025 years old, so we might see nodules on AC T that are not visible on a plain radiograph.
And we're not quite sure how to interpret these cases. They're not going to do as badly as those with the Mets that are visible on radiographs. I know they did do significantly, particularly in very metastatic tumours where, you know, the Mets are there, whether they're visible or not.
We don't really know yet. So I think for the time being, plain radiographs will allow you to get prognostic information from the public. Most of the publications that are available when we assess local lymph nodes start with an exam.
Are they asymmetrical? Are they enlarged and remember as well as the mandibular lymph nodes. You've got the medial retropharyngeal carotid zygomatic and the list goes on and bear in mind some very uncomfortable facts, like only 55% are read.
Digital metastases are to the mandibular nodes 55%. And like I said earlier, 60% of metastatic cases from lateralized lesions will have Mets on the other side. In this study of dogs with oral melanoma, 40% of dogs with normal size lymph nodes had metastasis 40%.
49% of dogs with enlarged lymph nodes had no metastasis. Remember that the oral cavity is very dirty. Dogs don't clean their teeth lots and lots of germs going on.
So there's very good explanations for there being benign enlargement of lymph nodes associated with the oral cavity. So how do we do this from a practise based point of view? The easiest is to FN a as many lymph nodes as possible.
Be aware that if you're doing FNAs, the accuracy in detecting mets is good, but it's not absolute. And in a lot of cases, non targeted lymph node resection can be considered, but it may miss a metastatic lesion just because there's so many nodes possible on one side or the other. Side, and you've got to bear in mind the morbidity associated with the dissection.
You know, the surgical wound, the pain the, extra time under anaesthesia, et cetera. So the cleverer way to do it, if again, if you have access to CT is using sentinel lymph node mapping in sentinel lymph node mapping has been very helpful for identifying one particular node to which the tumour drains. And if you need some support to do this in other tumours, we know that 40% of canine mast cell tumours have a sentinel lymph node, which is not the closest we've seen in the picture.
In the bottom, right, sentinel lymph node mapping involves injecting a bit of contrast agents around the tumour and then tracking how it migrates in the lymphatics with carefully timed CT sequences. Over the following few minutes, I'm gonna show you a a case we did here. This was a pug with a mast cell tumour over the frontal Sinuses.
OK, and this here is a blob of contrast. Agent. We actually injected contrast, agent, you know Rostral caudal left and right.
The tumour just a little bit and we can watch it migrating Now you see more contrast here, more contrast there, and you can see the contrast slipping down the right side of the dog's neck further and further and further. I don't say that going into the axillary node. So this particular tumour here was not draining anywhere on the head, really.
It drained into the axilla and a little to the pres CAPP. Knowing it was there meant we could then target those lymph nodes with considerable effort, even though they were normal size using ultrasound. So this is the the best gold standard way to do it if you have access to CT.
But then, in a lot of cases, sampling a few candidate lymph nodes is a way you can get by. And finally Step four in approach to an oral tumour. I would take a biopsy now.
I wouldn't do an FN a of these. We've got a dog who is anaesthetized, and if they're anaesthetized, I want a sample that will definitely give me the answer. FN a may give you the answer, but possibly for melanoma and likely for much more.
But a biopsy needs needs to be the the gold standard really. Now so some tips here. A lot of these tumours have lots of necrosis within them, and that's one of the reasons that makes FNAs quite inaccurate.
So I would take a biopsy from the centre of the tumour, often with a a long, thin device like a needle core biopsy or similar. And I would take several samples at different angles if you're taking a wedge biopsy, which is more appropriate for some tumours, depending on the location and the shape, please use Cory only for hemostasis. If you use Corry to carve off a chunk of the tumour, the pathologist may claim that you have created a lot of thermal artefact and you've obscured the real diagnosis.
So don't don't do that. Use a sharp blade and Cory just for hemostasis. And finally, you see, this dog here, this is this tumour here.
It's actually an osteosarcoma, the dog's mandible because it's right at the back of the CH the mouth. It's very tempting to try to get a biopsy through the skin V. Now, please don't do this, because if you do that, we'll have to consider the biopsy tract is contaminated, and it will have to be removed at surgery.
And if you're taking this dog to surgery, you're gonna do a very significant radical procedure. You don't want to lose the skin and the subcutaneous tissue underneath the bone that you could otherwise use for reconstructing the wound. So the best approach, hard as it may be, will be to chop off a chunk chunk of the tumour directly in the oral cavity.
Finally, some people, including some board certified surgeons, have asked me Well, we know this tumour is aggressive. We know, You know, just by looking at the imaging, we know how much bone is destroyed. We know it is a bad thing, A malignant process.
Does the diagnosis really matter? Can't we just remove it, send it to a pathologist and save the biopsy step? That's a very sensible thing to think.
But bear in mind, many variables depend on what the diagnosis is before any treatment is given. Yes, we'd like to remove all these surgically, as you can see here in the table. What if you can't?
What if the client, refuses, You know, what kind of treatment are you going to do then? And when we're looking, at surgery in particular. Actually, the surgery does depend on the diagnosis.
Because some tumours can be removed with a two centimetre margin recommended. Others need at least three centimetres. Some don't need any significant margins.
You need to just completely excise. OK, and if any surgery is not possible, then the response to radiation is hugely different. Melanomas.
Squamous cell carcinoma will respond very well to radiation. The fibrosarcoma osteosarcoma. It's an absolute waste of money and then with chemotherapy as well.
Some tumours like the squamous cell carcinoma. You can have a reasonable treatment with chemotherapy in a lot of cases, but very few other other ones will. So we've been through the four steps of the work up.
Now we've taken pictures of the tumour measured it, charted it. We've done enough tests to make sure that the animal's safe and hasn't got any co comorbidities. We've imaged the tumour.
We've imaged the Mets. We've sampled lymph nodes. We've taken a biopsy.
Now we've got a good data set of information here, and that can go into providing a prognosis. And remember, as I'll keep coming back to the stage as in the size of the tumour and its metastatic status is incredibly useful for the first step in prognosis. The diagnosis as well is very useful.
Some diagnoses are easier to treat than others. Some diagnoses have a much higher metastatic rate than others, and these are all in books. I'm gonna add a few things to this list, based on my experience as a clinician that you may or may not find in the books.
The first is the location in the jaw. A rostral tumour is much easier to remove than a cordial tumour. Therefore, we'll have a better prognosis.
The funding and the commitment of the client will always get you a better prognosis. And something that goes into the commitment of the client is the recommendation of the vet. If you or I are saying things halfheartedly or putting a a very negative tone on things, then the owners will pick up on that.
You know, you could, you might say, Well, you only didn't want to do anymore. But actually, the owners often want to want to do what we advise them, how we want to do. OK, so there's a lot of psychology going on if we're, giving off a kind of negative vibe about something the owners will will pick up on that.
And if if you want to start treating these tumours, we need to have a a balanced, realistic, view of things, something that can often deter a lot of owners and a lot of vets is what the surgical excision will look like. So in speaking to clients, I, I will often go through things in quite a lot of detail. This is a very ugly squamous cell carcinoma in a dog's jaw, and the dog from memory was only about two at the time, and I've convinced the owner that that removal of the tumour was the way to go.
That's what happened. And this is the dog now, and he's about eight. This was many years ago.
He's had no recurrence of the tumour, no metastasis. He eats very well. He plays tug of war with the Children.
He has a normal life with a Labrador just with his tongue lolling to the side of the mouth. This is another dog with a bilateral rostral Andy, and you can see it's more obvious here that it's got a short jaw, but it can still eat, can still pick up balls and play as normal. And for the maxillectomy procedures that in a lot of cases better, the surgery may be a bit more challenging.
But if you look at the image after the surgery, then you can hardly see any difference there. So it's important to give some time to considering surgery and discussing it in a balanced and realistic way with the owner making sure we don't give any, subconscious bias towards you being nervous about it or not knowing about it because that that will colour their their decisions. Good local control is the keystone in the management of oral tumours.
As we'll go on to discuss, the margins are required. Depends on the diagnosis, the complications. You can have haemorrhage, the essence or a nasal fistula epistaxis like the salivation, slobbering mandibular drift.
And these are all things that can be that can be treated. There's stuff we can do there. The worst complication is the one I've put in red here, and that's in complete excision.
That, might well be the result of a very big and challenging tumour. Fair enough, but We don't want it to be the result of a a nervous surgery because that can really undermine a dog's prognosis. Complete excision is the Holy Grail, basically in when dealing with these tumours and something that we can pass on to clients is that the owner's satisfaction with the cosmesis and the function after a surgery like this is well over 85%.
And if you compare that to a lot of other treatments that we do, I think it would be at least on par, if not better. And finally, there are some very exciting and really clever techniques to fit prostheses, to sites of mandom or mastectomy. OK, like this one here for a rostral mandom you a titanium implant.
And there's some BA case reports supporting this as well. I think in dogs they'd often do so well with a part of their jaw missing. It's not needed for function and an awful lot of these dogs.
However, there have been cases when I've had to put to sleep a dog, not because of the disease being untreatable just because the owner can't bear to think of them with part of their jaw being removed. And it would have been nice to think that if there was something we could offer those owners, which would have been, a prosthetic in the jaw rather than, having been a part of it removed the dog might still be alive, so I think they have a very important role in. In some cases, the other local therapy that I haven't mentioned much about today is radiation therapy.
And if you're unclear what I'm talking about with local therapy, I'm talking about a treatment that just focuses on the site of the disease or surgery or radiation and leaves the dog alone. Now, radiation therapy is incredibly useful for very complex anatomical areas here. Radiation can be used in two settings where you've got a gross tumour that just can't be removed.
Or, if you've, done a surgery, done your vest and only got incomplete excision. Radiation can be very important to mop up the remaining cancer cells and hopefully prevent tumour recurrence. And this is our linear accelerator at Bristol vet specialists.
And finally, people often ask me about chemotherapy treatments for, canine oral tumours or feline oral tumours, and I'm afraid I haven't got anything very, heartening to say there's very limited benefits when the tumour hasn't been removed. Now some tumours have a very high metastatic rate, and we can't really treat those with surgery or radiation. We have to use a systemic therapy, so chemotherapy is by default what we go to.
But it's still not a perfect treatment for control of metastasis. In some cases where surgery and radiation have been considered and have declined well, yeah, chemotherapy may have palliated benefit in slowing down a tumour or causing partial shrinkage for a period of time, and owners can be grateful for this. But I, I tend to talk about surgery and radiation as the first things I don't offer the owners chemotherapy at that exact point.
I want them to consider the gold standard first. If they say, actually this isn't for us, Then we can talk about chemotherapy, which is unlikely to be half as successful as a local treatment would, and that helps to keep things a bit simpler for them. If you mention there's chemo, there's radiation, there's surgery.
They tend to get a bit scared of all these options, and a bit unsure in my experience. So that's it, Really. That's my investigation of oral tumours.
I went through it in some detail because, that's all the information I commonly work with every day when I'm doing these. Let's talk about some specific oral tumours now. And the most common one in a dog is the oral tumour.
Is the oral melanoma Rather, this tends to occur more in smaller bodyweight dogs compared to the other oral tumours Mean age of about 11. You can say good example in the top right here, a melanotic, a black or melanoma. And you can also see, amelanotic oral melanoma in the bottom right, so they don't have to be black.
OK, if you get a an oral tumour that you biopsied and the pathologist comes back and says, I think this is an aggressive, cancer, but I can't tell you which one. The chances are that's going to be a melanoma. Melanomas can be very, very variable.
In their appearance on histology, they can sometimes look like spindle cells like fibroma. Sometimes look, fibrosarcoma can sometimes look like round cells like a lymphoma. And there what's good is that there's a lot of useful immuno to chemical tests that you can employ to find out which type of tumour you've got.
Now, with melanoma as well as being the most common tumour, it is a very, very metastatic tumour, and that sets it apart from many of the other common oral tumours. OK, it is strongly trophic to lymph nodes both on the left and the right, no matter what side the tumor's on. But still, you can have very good survival in these cases, particularly if you pick them up and they're small.
Melanoma can also be difficult, and that on rare occasions the pathologist might say, I think we've got a benign behaving melanoma here. It doesn't happen very commonly, but we might see this in my clinic, perhaps once a year. Now, to be benign behaving.
It needs to satisfy a lot of criteria. The first one is we need to have melanocytes or cancer cells rather that look very, very similar to the normal benign melanocyte. They need to be very well differentiated, and if that criterion is fulfilled, then we need to have a very low mitotic count and everything else in this table here.
I won't read it all out. Is satisfied. Mitotic count is the most useful one for me as a non pathologist because it's something that's quantifiable.
But the pathologist will have to go through these in detail to see what we've got. If there's any doubt, there's a very useful, prognostic panel that's available at Michigan State University. So I bear this in mind, but in most cases, or if there's any doubt, we'll have to consider that the melanoma will behave aggressively and metastasize like wildfire.
So to remove an oral melanoma, we need two centimetre margins around it, and we need to bear in mind. It could well have spread to a lot of lymph nodes. If there's any suggestion that they're involved, I would try to get them removed as well.
Now, if you look at some of the published data, the widely published data, you'll see that survival with surgery alone is between five and 11 months, with a third of them alive at one year. I think we can do a bit better now. On the one hand, we know how to do oral surgery and dogs a bit better, and on the other hand, we found that other things can contribute to survival.
The first one is stage. Look at this data here, and this explains why I keep mentioning stage. And, I'm repeating this for a reason throughout this webinar, because I like people to remember that stage is very useful.
So if you've got if you ring me up and you say you've got an oral melanoma, I don't think it's metastatic. What's the prognosis? My question will be how big it is, because if it's Stage one, then you'll have an average survival time of over two years with surgery alone.
And if a dog's 11 at diagnosis and we get to 13, well, we may not need to give any treatment for the metastasis. It may be that surgery is all that's required if the melanoma is over four centimetres, however, we're likely to be looking at months, and we're gonna need to talk about other treatment from surgery to try to slow down the metastasis. Secondly, location in mouth is likely to invent survival.
If it's, on the lip or the tongue easier to resect, you'll have 100 and 50% survival compared to maxilla or mandible, where you need to do a harder surgery. This is also a reasonably recent paper, and it showed that the average survival time often in some very advanced melanomas. You know where, for example, a lot of these had, you know, stage three or Stage four tumours.
The average survival was two years, and the majority of these guys didn't have any adjunctive therapy like radiation or chemotherapy. The key here was that, almost three quarters got complete excision at surgery, so it's not going to, cure the tumour. But possibly the most prognostic feature of an oral melanoma case is good control of the disease, a complete excision or, if you haven't got complete excision radiation therapy to consolidate the work of surgery afterwards, and this will pay dividends, the tumour tends to pick on old dogs and the rate of metastasis if it is reasonably slow.
So you can get a good prognosis without necessarily curing the disease by just getting really good control of the tumour in the mouth. If surgery isn't possible, you could do radiation therapy without any surgical debulk Typically, melanomas respond really well for melanoma. We're often giving one dose of radiation every week for four weeks.
So that's nice and cheap, and we can also radiate the lymph nodes. We don't have to pick out this lymph node or that lymph node. We could just radiate the lymph node be and that often does, well, almost as well as surgery.
Again, the old data shows similar type of surgery, but I think now we're treating them better. I my ex. My feeling is they're doing better now.
We do need to consider systemic chemotherapy as well after we've controlled the disease in the mouth. Carboplatin is something to consider because in the gross that is non resected tumour state, about 28% of them will shrink when you give carboplatin, and we can extrapolate that and suggest that it may be the same in preventing metastatic disease. There's limited evidence for temozolomide as well.
In a lot of cases, I would tend to give metronomic chemotherapy, and that's been shown to have some benefit in, admittedly not a large data set. And there are also anecdotes of melanoma shrinking with use of the Sein Palaia. There's a very, very chemo resistant disease.
And this is a brilliant picture that my colleague Ivan gave me up in the top. Right here this shows a lymph node being extirpated. OK, surgery.
And it also clearly says the reason why we need to give chemo because lots of these little kind of satellite melanomas all the way down the lymphatics we're never gonna remove all of these As much as surgery could remove some of them. So this is the reason why medical therapy is needed. You can see in this picture the metastasis occurring.
And of course, I have to mention as a medical therapy, the DNA vaccine that we have available, tyros inase is a protein expressed in the expression in the production of melanin in a melanocyte. So it's a very good target because this protein doesn't exist in other cells and you can be quite specific to try to aim the immune system to target cells with thy Rosina. And the way this vaccine works is transecting cells with the human version of tyros inase hoping that the cells will take up and start producing a human protein, which looks structurally slightly different to the canine one.
And this will wake up the canine immune system to think Hang on. This, tyros ASE is quite abnormal. These are abnormal cells.
We need to attack them. And almost 20 years ago, now it was trialled and very, very impressive results. The average survival couldn't be calculated because most of the dogs remained alive and that was corroborated by another study and everyone was very, very excited.
But a couple of years later, people started getting a bit more suspicious when it was trialled in field conditions because something was obviously different in the field conditions and there was often no significant survival between the vaccinates and the non vaccinates. This is a study from the UK, admittedly only 32 dogs and there there's no significant difference in survival between those who had the vaccine and those who didn't. But I wouldn't give up completely on the vaccine.
And this study, also from the UK shows again, nothing had a significant effect on how well these dogs did on multi variable analysis, and that includes the use of the melanoma vaccine. How about that? It's not the end of the story because in this study there were eight out of the there were 13 dogs who didn't have the tumour removed.
They just had, the melanoma vaccine, and eight of them had tumour shrinkage. 11 dogs in this study had long term survival far in excess of what they're expected to do, and three were still alive at the time of publication. And there were two patients who had Stage four disease that has spread to the lungs, and they lived far in excess of the time.
They should do so this then, I think. And it explains quite neatly what immunotherapy is about. Because immunotherapy very rarely works on everyone.
In a population, it usually just works on the minority of individuals. That's because all cancers are different and all immune systems are different, and both cancers and immune systems are very complicated. So immunotherapy will have a benefit on the minority of dogs, and we think that's around 20% ish, and that can be a hard sell to owners saying, I'm gonna give you a treatment where in 80% of dogs, it's as good as wasted.
But in those 20% of dogs that do benefit from the treatment. It can be pivotal. It can give them their life back.
It can give them a prognosis that you couldn't dream about. So if our clients are able to afford it, I do offer this vaccine, and I'll offer it often alongside a medical therapy like metronomic chemotherapy. The use of this vaccine I call immunotherapy should be for the prevention of Mets getting bigger or Mets kind of developing.
Rather, once a gross tumour has formed, it will have a protective framework around it if you like, and the effect of any immune system is going to be very, very minimal. So this vaccine is licenced for the cases that have had good control of the primary tumour, with surgery plus minus radiation. And we're just trying to prevent Mets from developing.
It's much more likely to be successful there, even though there are some exciting anecdotes of a gross tumour shrinking. We should try to use it, as it is designed to prevent mets occurring, So melanoma is a very chemo resistant disease, I told you. Carboplatin has a response rate of about 28% and melanoma vaccine about 20%.
It can be very difficult for a client to justify spending the money on treatments. And I, I haven't got a very cheap way of doing this, but I think of it like a sum of fractions. If you say, gave carbo and you monitored to see if anything was working.
If it wasn't and he gave something else monitor to see if something's working, it wasn't. He gave something else and so forth and so forth. You'll be adding up a say, a 28% chance of working with a 20% chance of working with, say, for example, a 15% chance of working.
By the time you trial. A few therapies you're likely to have a you know, a chance of something having worked that exceeds 50% and we can get good responses to medical therapies in melanomas. In dogs, you can get some very good responses.
I've seen some with, the, for example, where the tumour shrunk down and stage shrunk down for a long period of time. Even Mets having disappeared. So it's not the case that it's a uniformly resistant disease to chemotherapy.
It's the fact that it's inconsistently responsive to chemotherapy. And if the client's motivated, it's well worth working through these treatments to find what works for you. Let's move on.
Now let's talk about the squamous cell carcinoma. Two comments on this Since this is an epithelial tumour that originates from the lining of the me, I find that these more often than not are ulcerated diffusely from the start. It's also a tumour that has been associated with hypercalcemia, and we often forget that in dogs, we think of renal gland tumours, multiple myeloma, lymphoma.
This is also something that can cause hypercalcemia for the common squamous cell carcinoma that occur on the gums. It's much, much less metastatic than the melanoma, and so much so that in a lot of cases we just talk about local therapy, and we don't tend to talk about systemic therapy. It's, about, 3 to 36% could spread to the lungs, and often the lymph node met rate is less than 10%.
Again, we like to remove these with two centimetre mark. Oh, James, we're looking at the picture on the right. I think that might be a tall order here if it's on the mandible Easier surgery.
And we would expect a survival of 18 months to two years, a maxilla about one year to 18 months and, correspondingly, a higher response rate. But again, this is relatively old data, and stage once again is very, very important if you get a scream in a dog less than two centimetres, and it's difficult to calculate a survival because they all remain alive at the end of the study period. And that's good.
But again for the stage threes, then, survival. More like a year with surgery. They'll often respond well to radiation therapy if surgery is not possible.
But now, with this disease, we're gonna need to give lots of small doses of radiation now melanoma. We might give four doses once every week with a squamous cell carcinoma. You might give 15 to 20 doses, you know, 56 times a week, OK, just due to different biology between the tumours with radiation therapy again, you get similar.
Recurrence rates similar survivals for surgery. But for the cases that have radiation and surgery, the two seem to be added him and the average survival time surgery and radiation is almost three years. You can also treat these with chemotherapy, which a lot of people seem to forget.
And just with parox cam alone, one in five will shrink. And I don't think there's anything magical about parox aam. We we latch on to it as having magical anticancer effect in veterinary medicine.
In human medicine, the jury is out. It is shared by anything that will inhibit cox not just parox aam bear in mind that Perox cam isn't licenced for dogs in a lot of jurisdictions. And it's also very good at causing gastrointestinal and renal adverse effects.
So I would advise you to use a licenced, and better tolerated crop inhibitor and expect the same outcome. But look at the bottom here. When you use carboplatin inject toly every three weeks in parox, 60% of these things shrank and that remains so for 18 months.
Cisplatin is also being used. Cisplatin was the, as an older drug of the same plaster carboplatin. It is a very efficacious drug, and I think it still succeeds where carbon plain may not.
But cisplatin is incredibly nephrotoxic, and I would be very nervous to use it in my clinic. If the if the need arose, I'd recommend people who don't give chemotherapy much to steer clear of cisplatin. And finally, there's some, you know, interesting data with use of palaia to seib, 75% of tumours respond, and out of those, it's 62.5% that shrank a little bit, and the remaining 12.5% just stayed the same size.
And the average time of that response was five months. There's also anecdotes of success with metronomic chemo, thalidomide or paclitaxel should that become available. So if you're willing to treat these, there's a lot of options with these common ging squamous cell carcinoma.
I'm gonna show you another carcinoma now the tonsilla squamous cell carcinoma. Here it is. And this, I'm afraid, is a totally different kettle of fish.
If you look at the tonsilla qua here, it looks a lot more innocuous than the ones I've just shown you. But the problem with the tonsilla squame is this. This is a metastatic retropharyngeal lymph node bulging into the pharynx and pressing on the larynx of this poor dog.
There's a phenomenon here that's similar to the anal gland tumour, where you can get very, very large metastatic disease that tends to cause the problem from a very, very small and innocuous looking primary tumour. So the tonsilla squamous cell carcinoma, then, is much, much more metastatic and has a similar rate of mets to the melanoma. If we're treating these, therefore, we need to think about a local treatment and a systemic treatment one to address the issue in the mouth one to address the meta metastatic disease.
The presentation's interesting because the primary tumour is often very small. It may just present when it's metastatic and the owner brings in the dog. It's fine, but I was stroking him or looking in his ear the other day, and I found there's this huge swelling on the side of his neck and he might biopsy it, and it comes back with a squamous cell carcinoma.
Sometimes they present you to disease in the pharynx. They might cause coughing or retching or, clearing the throat a lot or reverse sneezing. But equally I think that the cervical lymph megaly is very common.
They can also be bilateral. Some dogs, they occur bilaterally, which is frustrating as well. And if you see bilaterally enlarged and abnormal tonsils, you might think well, is this a melanoma metastasis or is this lymphoma?
So it's a very different biology of disease here, and something that's that's interesting is that this one more so than the other Squam is strongly related to environmental pollutants. In a lot of cases of squamous cell carcinoma of the tonsil, I found that the the dog, smells heavily of cigarette smoke, for example, so with these, we'd always consider it a systemic disease and bear in mind that, you know, up to 73% metastasize, ultimately, but 20% are metastatic diagnosis. It's also very resistant to chemotherapy treatments and surgery.
OK, in contrast to the ging of all versions. So with radiation or surgery, you can get good local control, but still 10% survive one year with radiation and chemo. You get, average survival around six months whether we are outliers, but so the way So it is tough, but the way you have to address it with good local regional therapy and then a bit like the melanoma sequentially using drugs to find out, what outcome can be achieved?
There's actually not much been published about the tonsilla Squam until recently, and this study came out a couple of years ago, which I think it's a really good study. And you can see here what was found to be prognostic. We found that if there was no metastatic disease at diagnosis and bear in mind, that's 80% of dogs.
The average survival is about a year if you treat them and then if you do tonsillectomy on its own average survival about, 67 months. And if you're giving adjuvant chemotherapy, that's tonsillectomy and then chemotherapy. The average survival is not much more, to be honest.
So what this says is that you can get a, you can get a good outcome of about six months with surgery and chemo, and if you don't have meds, then you could hope for survival of up to about a year or so. Finally, you can also get to squamous cell carcinoma at the base of the tongue, and I consider these intermediate in between the gable ones and the tonsilla ones. They have a much higher metastatic rate than the ginger ones, and they are much less responsive to radiation or chemotherapy.
I get the feeling, and it is a feeling because there's very little published on these that they're not quite as aggressive as the tonsilla ones. They're not quite as resistant to treatment, but perhaps I'm imagining it It It's seeming quite neat to imagine that as the Squam get more cord in the mouth, they become more aggressive and more resistant to treatment. And so this would be intermediate between the tonsilla and the ginger ones.
But actually a lot of data to date, and there isn't much. But a lot of data to date would put them more in the tonsilla category, with very little difference. We've got the oral fibrosarcoma here, the third most common, oral tumour in dogs, and this is a disease of large breed dogs.
Most commonly, the average age is about 7 to 8, and the thing with these that can often keep catch people out is that they may look histologically benign, and you may have a very aggressive tumour in the mouth with very aggressive imaging, but the pathologist tells you know it's a fibroma don't be fooled by this. Think of the high low phenomenon that is a high biological aggression but low histological aggression, terminology that we use. One thing that can help pick them out is that they tend to be on the hard palate or the maxillary arcade.
They tend to be in large breed dogs and that in the early stages, at least because it's a tumour from deeper tissues, I don't often see them as ulcerated, as the oral squalls tend to be, or as friable as the melanomas tend to be. They have a metastatic rate similar to the squamous cell carcinoma of the gingiva, and we could almost forget about metastatic rates because these are very, very, very invasive. If we can't deal with the local tumour in the mouth, then the the presence of metastasis is almost inconsequential.
To remove these, it's recommended to have three centimetre surgical margins around them, and if you do surgery alone, the early results were 50 to 60% of them occur, and only about half of them live to one year due to the local disease. If you use radiation on its own, you get a poor response so surgery and radiation gave the best chance of control, and the average survival was 1.5 2 years.
About a third recurred, and 75% would be at one year. Remember that radiation, that the sensitivity to radiation will be increased when you reduce the bulk of the mass, because more cells are then forced into the divi phase of the cell cycle. So if you reduce the size of the mass, you'll make it more sensitive.
And that's why we have a discrepancy here. Between radiation alone have been a poor response and not being worth it, but surgery and then radiation to mop up Microscopic traces of fibrosarcoma have been a much better outcome, so that's kind of what's in the textbooks. But some quite recent, more recent study here rather has shown a much lower recurrence rate.
Now we're having definitive curative, intense surgeries. Average survival is longer two years, 90% are alive at one year, 60% at two years, and the difference here is that we're resecting them better let me say again that good local control of the tumour, principally surgery, is the keystone in managing oral tumours. And for those dogs with complete margins, the average survival was over four years.
The good outcomes are possible just quickly. Then we'll look at some of the less common tumours here. Got the oral osteosarcoma.
Bear in mind that you know, we think of bone, limbs when we think of osteosarcoma. But about a quarter of osteosarcoma cases are on the axial skeleton, and half of these are maxilla, or mandible, much lower metastatic rate than the ones on the dog's limbs. It's believed to be between about 37 and 60%.
With more recent publications, the metastatic rate is going up because we're getting better at treating the local disease, and we're realising that more of them are metastatic than we initially thought. So with surgery again, you can still get quite good survival times in the age order of 14 to 18 months for mandom, 5 to 10 for the maxilla. But again, local control is key.
Complete resection four years incomplete resection 6 to 7 months Because of the metastatic rates being, significant. I tend to offer chemotherapy for these, just like I would for one on the limb and the adjunctive. Chemo results in significantly better metastatic free intervals, and the last canine one we'll look at is the acanthoma ameloblastoma, as it's currently called, depending on when you're into vet school, you may call it an acanthoma Elis, an adamant toma or basal cell carcinoma, And I wouldn't mind betting that in a couple of years it will have a different name.
But there you go. This is a tumour of, dental ligament origin, and most commonly it pops up alongside a canine tooth like the pictures on the right. It's quite a nice thing to deal with because it's not considered to have a metastatic rate.
It will behave aggressively, though, because it will, expand and expand and cause a lot of pressure damage within the cavity where it sits and it can weaken the jaw. What could cause a fracture? So, segmental Hemi man or maxillectomy is all you need without significant margins.
If that's not possible, radiation therapy can also give you a good outcome. And intralesional Bleomycin has been reported as a complete response in four dogs often lasting over a year, which is interesting, but I'd rather not do intralesional chemotherapy in my clinic for health and safety reasons. So to finish off, then let's look at our feline friends.
And remember, there's fewer tumours that these guys get as the horror that is the squamous cell carcinoma. And then there are sarcomas making up, the rest of the majority now for a feline squamous cell carcinoma. Ideally, we'd still recommend two centimetre margins to excise these.
That's because, a cancer cell, or rather, a cell in a cat is of similar size to a cell in a dog, regardless of the size of the whole body of the animal. You know, if so, in a great Dane, it's gonna be very similar to that of a cat. So, when you look at a tumour, that is for the sake of arguments three centimetres across, it will still contain the same number of cancer cells and therefore be biologically the same entity with the same capability of a aggression, whether it happens to be in the mouth of a small animal or a large.
So we still talk about two centimetre margins being ideal. But if you think of two centimetre margins in a cat's mouth, by the time a tumour has been recognised, then that's most of the cat's face, isn't it? So it's not really practical to achieve that in almost every case and for the fibro sarcomas that you know the issues worse, they're more invasive.
You recommend at least that, and one of the things that makes oral tumours in cats a sad topic is because they do tolerate oral surgery, even relatively conservative oral surgery quite poorly. They often have very poor post operative function of the jaw. They'll often have drifted the mandible to the side that's been removed might traumatise themselves often.
They just don't want to eat and need a feeding tube for extended periods after surgery. In this study here, almost all of the, manul toy cats had acute complications. Three quarters.
It was not eating difficulty eating. 41% needed an O tube. I mean, almost 80% had long term complications like difficulty grooming, which cats hate.
T is which cats hate or the mandibular drift, which again they hate, and because of the sharpness of their bottom teeth, they could cause a lot of damage to their upper jaw and the proportion never regained the ability to eat. So it's a really depressing thing when you have to consider oral surgery on a cat radical or surgery. So some very clever prosthetic techniques to replace bits of jaw have been, pioneered.
And there's some case reports here in a cat. And I welcome things like this because as well as being more acceptable to owners, I think it could be tremendously useful in maintaining post-operative function if done correctly in cats. And this could potentially change the prognosis for tumours in cats, but it's not yet, commonly used or well tried and tested.
Feline maxillectomy is actually a bit better tolerated in Feline Mandiri toy just because of the bracing effect of the ma nasal bones in the maxilla. You can see a small, benign mass here, being removed. It's not so benign, actually, in this case, but for things like this, more definitive surgery would be possible than the mandible.
So let's look at the oral squamous cell carcinoma, which will be most of the feline oral tumours. You see, there's parallels with the tonsilla squamous cell carcinoma in dogs here with a strong environmental component in carcinogenesis, and risk has been reported to increase their use of flea collars and exposure to household tobacco. The feline tonsillar squamous cell carcinoma exists as well, but there's not much clinical difference in behaviour between that and the more common squamous cell carcinoma of the ginger, the or the base of the tongue in a cat contrast to dogs.
And these things are very, very invasive. They're invasive of the bone, more so than in dogs. Metastatic rate is low and largely unimportant.
If we can't control the tumour in the mouth, then we can forget about the metastatic rate, a very resistant to chemotherapy and radiation. Regrettably, in one study of cats treated in general practise, the average survivor was 44 days. Now we can consider other things, surgery with a marked complication rate, I've said.
And see the surgery and radiation, which has, I think, for the right lesion, potentially a better outcome. But the failure of local control and the tumour recurrence is reported to be the cause of death. In 86% of cases, these things are very resistant to radiation, and in the benefit of time, I won't do that in won't go through that in much detail other than say that with radiation, the outcomes have been temporary, transient.
Despite very heroic, protocols that have involve radio sensitization with drugs and sometimes twice daily treatments. You tend to get a very temporary response with that. Again, with chemotherapy, it's very resistant.
There's a lot of necrosis in these tumours and necrosis isn't gonna shrink with it, no matter what chemotherapy you give. There are anecdotes and some some small data sets showing that palaia can give a temporary response. And that's quite interesting.
And this is something that we could consider doing. You know, it's a reasonable thing to do in cats if in practise, if your cat is otherwise quite comfortable. So in this study here, which is something that we could all use in clinics the way we use the non steroidal and palaia, almost 60% responded.
Now, most of those with disease just not growing and not shrinking. Some of them had tumour shrinkage and the average time, for which this, you know, the cat survived was about four months. I'll show you a picture of the kind of response you get when you put one of these guys on palladia.
You see the lobe, the pink lobe of the tumour? That's ostra. That seems to have gone The more cordial bit that's necrotic remains the bit is dropped off.
Possibly so it will still cause this failure and discomfort, and we need to treat that medically. But, it will at least, have improved the situation a little. Fine.
So I think that the most pragmatic thing we can do when we get an oral squamous cell carcinoma in cats is to consider the supportive care we could put them on non steroidal inter seib. If they're eating and you're happy with their quality of life, I'd be very careful going for more definitive surgery. Like radiation?
Or is it more definitive treatment like surgery or radiation because of the limited benefit? Any benefit being temporary, and certainly in the case of surgery, some of the adverse effects can be severe. But I might consider a more heroic treatment if we accidentally find a very small lesion at a dental.
And we feel we've got time to, you know, to do something to try to get rid of this more, thoroughly. If we're able to do a surgery and get a more complete excision and then consolidate that with radiation, then we just might have a fighting chance of a good outcome. The majority, though, when they're quite big.
It's a sorry story. So in this majority, I would consider things like nonsteroidals might consider rab sublingual buprenorphine. You could consider palliative radiation therapy, which is a much more less intense treatment just to control the pain.
You might want to ask a local specialist anaesthetist about any long acting local anaesthesia analgesia that may be available wanna treat secondary infection. And above all, you wanna make sure that you're monitoring their quality of life, their appetite and their body weight. And this can be a really useful thing to employ some of the, nurses and technicians in your practise to regularly weigh them.
They regularly stay in contact with the owners and answer any questions they have. For things like this. There's these quality of life monitoring tools, which can be really useful to fill in with the owners and get the owners to fill in at home, and I of with most of the feline oral Squam I treat, I don't find them a good candidate for any definitive treatment, as the tumours are just too big.
So I talk Talk about nonsteroidals, the Seren, lots of analgesia and, above all, good nursing and good quality of life monitoring. So my last note on the feline oral Squam then, is to compare, and contrast the behaviour of squamous cell carcinoma in different locations and species. Don't think that a squamous cell carcinoma is a squamous cell carcinoma because it's not OK.
The ones in the mouth of the cat or on the nasal plan of a dog are very invasive. Long term controls difficult. They're resistant to drugs and chemo.
The ones on the nasal planum of a cat or in the ginger there of a dog are less invasive. You can often get a good outcome with surgery, radiation and or chemo, so we need to think of the exact location and the exact species. And finally, I've just got two slides on the feline or sarcoma.
I find that sometimes pathologists might think it's a fibrosarcoma or an osteosarcoma, and they might offer immune histochemistry so they can't be more specific without that. I don't often do that immuno histochemistry because I think, I know enough already. Surgical control is key, and complete excision may be curative if it's possible.
In a lot of cases, it isn't, however, for the reasons we've discussed the cats tolerating oral surgery, poorly surgery and then, radiation is probably likely to be the best way forward, like in the dog. But radiation on its own and chemo on its own are unlikely to be of benefit again. It's metastatic rate is low, and we can almost forget the rate of metastasis.
If we can't deal with the tumour in the jaw and this brings me to the end, I'd like to conclude by saying that oral tumours have a relatively stereotyped investigative approach, and a finite list of differentials covers most cases. Surgery should be the first consideration in oral tumours, but knowing the diagnosis will tell you necessary margins, likelihood of cure and adjunctive therapies which may be needed. Most canine or tumours, have a metastatic risk, which is much less important than local invasion.
So local therapy, the surgery and the radiation is where you should invest your effort. Melanomas and tongue base or tongue tonsilla Squam are the exception, and medical therapy is indicated to control the risk of meds. Most oral tumours in cats have a small, metastatic risk, and the same diagnostic and therapeutic principles are true in cats.
As for dogs, however, survival times are usually not as good or interfer. Cell carcinoma has been extremely aggressive and poorly tractable with radiation or chemo. Finally, multimodal analgesia, bisphosphonates and quality of life monitoring are often prudent palliative measures, but any oral oral tumour, which is not having a definitive treatment if you're interested in further reading, with own McEwan, small animal oncology and thrall's textbook of the Veterinary Diagnostic Radiology, you'll be able to explore many of the things I've mentioned here.
If you're interested in oncology, please consider joining the Esk Facebook group or the veterinary cytology Facebook group. And finally, this is where I work at Bristol Vet specialists. We offer radiation therapy, and if you're looking for other places offering radiation therapy, here they are in the UK at Southfield Referrals and the universities of Cambridge, Liverpool, Edinburgh and Glasgow in the UK as well as at Lille in the French border and Paris a little bit further.
AFI I like to acknowledge my team the fantastic people I work with every day and congratulating her senior nurse on passing her BT S exam. Thank you ever so much to webinar vet for having me on apologies. I've run over a bit today and thank you to Mark and Rebecca for organising this evening.
Look forward to speaking to you another time. Bye now, right? Thank you very, very much.
Owen really, really enjoyed that. Thank you for a very excellent session. It's a pleasure listening to someone who not only knows it, but just explains it so elegantly and and thoroughly.
And I'd just like to share the thanks from the webinar of it for on being here and thank you to all the attendees watching tonight If you in addition to all the excellent resources, if you're interested in more, we have several other webinars on oncology by Owen here on the webinar event itself. So thank you very, very much and hope to see you soon. Bye.