Dog Oral Malignant Melanoma?
Hi everyone, welcome back to the article. This article is about oral malignant melanoma. I also posted another article on melanoma so if you are reading this I would like you to come back there will be a link below about the other article as it was about an overview of what melanoma is and some of the other locations we see. So I was talking about skin melanoma in that article, we also talked about finger melanoma. But in this article, we’ll focus on oral malignant melanoma, the number one location, and the most common oral cancer we see. So let’s dive in, we’ll cover surgery, radiation, systemic therapy like immunotherapy vaccine, and some of the prognostic factors.
So let’s dig deeper, analyze it. So here we are at oral malignant melanoma. So of the oral tumors, malignant melanoma is the most common, but it is not the only tumor we see in the mouth of dogs. We also see things like fibrosarcoma and squamous cell carcinomas. And a good general rule of thumb for mouth tumors in dogs is that they have a better prognosis if it comes from the lower jaw, jaw and towards the nose of the dog rather than further back. And a lot of that has to do with accessibility for surgery and being more surgically resectable. Therefore, it is easier to remove a tumor in the jaw than in the upper jaw and towards the nose of the dog. The maxilla is connected to many of the nasal bones and it can really get more complicated to do surgery.
So that’s a good rule of thumb for all oral tumors in general. So the lower jaw more towards the dog’s nose than the back of the dog’s mouth will be easier and those tend to have a better prognosis, and many of those are more likely to be removed with surgery. margins. But then what are the dogs we usually see with oral malignant melanoma?
I told you they are usually very pigmented varieties. It will be dogs like Scotties. We also see them in other breeds. Golden Retrievers are more representative, Chow, Poodles, Doxins, unfortunately, we see them in Black Labradors too. And we also see them in mixed breed dogs. It is usually cancer in middle and older dogs. And these are cancers of which, you know, I think there are two fronts. They are very invasive and can often grow locally to the bone of the mouth and the top and bottom bones, depending on where they are. And the second front is that they have metastasized strongly so they can spread to those lymph nodes. We also talked about the liver, lungs, and other organs.
So simply removing the tumor from the dog’s mouth will not cure dogs of these cancers and they have very spread. And I will warn you from time to time that they will do a biopsy and tell you that this was a benign one from the mouth and, in general, most dogs with oral melanoma are malignant until proven otherwise. And I’ve seen some who have had those biopsies that indicate benign behavior or a benign biopsy, and they tend to be malignant. Then they just warned me. Some that are more labial may work better and are also easier to operate than some that are more invasive to the bone. But then again, they tend to be quite aggressive cancers, both in the mouth and with high metastasis. For things that have been shown to be a forecast, size has certainly been shown to be a forecast, and when we talk about the staging system for that size, it comes into play.
And then it decomposes, but the smaller we can find them, the better they do and whether or not they have spread to the local lymph nodes and whether they have spread remotely to the lungs and the different organs that we have. they turn out to be prognostic. Also, other things incomplete margin, which is why dogs with incomplete margins in one study were three and a half times more likely to die from causes related to the tumor, be it regrowth or metastasis. So I really emphasize how important it is to try and find these tumors early and treat them with surgery or radiation or some of the things we’ll be talking about. So again, it is really important. Also, something else to emphasize with the highly metastatic speed are these lymph nodes. In dogs that had large lymph nodes in one study, 70% had metastases but normal lymph nodes in the study, 40% had metastases, just to emphasize that normal lymph nodes should definitely be treated with lymph node aspirates.
And also the lymph nodes are positive for metastases, which changes the stage and changes the prognosis of the dog. That’s why we want to do it. So what proof does your dog need? Lymph node aspirates, chest X-rays, ultrasound, will be part of the study. And I recommend it for surgery. So if oral melanomas, oral melanomas are surgical, they can be removed if they aren’t too big, you know, further to the front of the mouth, surgery is our best treatment option.
For the dermal, the numbers, you know, surgery is sure to be the main treatment of choice for the local disease, so that the tumor grows. But the problem is that many of these substances, especially in the back of the mouth, can be very invasive to the bones. So if there are any questions, we often do a CT scan. Another really important thing is to run that CT scan before surgery and not try to remove it and then go back and find out where they didn’t hit the margins and things like that. So really a CT scan for this complicated one, this big one, will be really helpful, and I often think it’s a good idea to see a board-certified surgeon first as they often have to remove part of the jaw, or They’ll tell us surgery is not an option and then we’ll look for a plan B-like radiation, which we’ll talk about in the next section. Okay, radiation actually plays an important role for these dogs with incomplete margins or non-surgical, unresectable mouth melanoma.
we will post a link below. And I usually leave it to the radiation oncologist because I’m a medical oncologist and not a radiation oncologist and sometimes protocols change. But the take-home message is that because of the way melanoma cells respond to radiation, they typically irradiate them weekly for about four to six treatments. And that means there isn’t much anesthesia and not many side effects on the skin and mouth. So there is not much combustion and things like that. So it can be a very good alternative option for these non-surgical cases. This is often referred to as a hypofunction protocol. This is what they call it with pretty decent response rates. Therefore, in these non-surgical cases, I will often use radiation and refer them to a radiation oncologist after consultation with the surgeon. So we all need to work together on these matters. Often the radiotherapist will treat the lymph nodes, if they are positively confirmed with lymph node aspirates or even prophylactically, they will only treat the neck area if there are microscopic cells. So that’s also an advantage of radiation: we can treat the lymph nodes and destroy all those cancer cells with radiation.
So now we have treated the local disease with surgery, maybe the mouth with radiation, but now we have to do something about that second front, right? System sickness. Preventing cancer from spreading, you know, is our goal. And therapy is always best before cancer has spread. And the treatment that we will normally have on immunotherapy is certainly more effective before cancer has spread. That’s why we want to do these chest X-rays, ultrasounds, and lymph node aspirates. Chemotherapy has not been shown to be very effective for this, people have looked at carboplatin and a few other chemotherapy drugs, but some efficacy has been shown,but no, you know, it’s not very effective.
So a lot of research has been done since the days of my residency at the AMC with the immunotherapy vaccine for canine melanomas. And again, I always remind people when we talk about vaccines because we’re thinking about giving your dog the rabies vaccine to prevent infectious disease. This is a vaccine, it is immunotherapy after your pet has been diagnosed with cancer. It is an immunotherapy vaccine used as a treatment after cancer has been confirmed and cannot be used to prevent cancer. And this is a vaccine that is now commercially available. It’s called a starter vaccine. It’s a plasmid DNA vaccine. It targets something called tyrosinase in melanoma cancer and it has been shown and there are studies looking at it for both the oral form of melanoma and the finger. And for the oral,
If you look at the dog’s disease-free interval, then these are dogs that had no metastasis and then had surgery or radiation, something to control the local disease in their mouth and then get the melanoma vaccine, their cancer didn’t come about 16 months back or had metastasized, which is great. Typically, with surgery for melanoma alone, we see our survival times of about six to nine months and mean survival times of about 22 months or about 680 days. So definitely an improvement there. 70% of dogs are alive after one year and about 30% of dogs are alive after two years. How the vaccine works, it’s an intramuscular injection, it’s given two weeks apart for four doses, so it takes two months. And then dogs usually get a booster shot every six months for the rest of their lives. And that’s something I’ve been doing since the vaccine was approved, I mean 2008 and we keep using it and I think the vaccine is now available through BI, originally through Marielle. So you know, something to talk to your cancer specialist about and it is only widely available through cancer specialists. So it will not be something that you get from your doctor.
So you can talk to them or consult a cancer specialist, but certainly, the systemic therapy that I recommend for my patients with malignant melanoma, both digital and oral. And that concludes our article on malignant oral melanoma. I hope you found it helpful. Remember, there is one part, another part where you can go to get that overview on melanoma if you haven’t seen it yet. And don’t forget how important early detection is when we’re talking about size as important and how hard it is to get a really good exam, you know, and we have to be careful when we get into our own pet’s mouth. And their vet, a great opportunity for them and a vet to get a great oral exam is when they go to their dentist. So for most middle-aged and older dogs, we recommend dental surgery once or twice a year. So that’s a great way to not only brush your teeth but also evaluate these oral tumors. Again, I hope this article has served you. Thank you very much for reading and hope to see you in the next article.