There has been much online talk these days about dogs with mast cell tumors (read, Palladia) which are the most common canine cancer.
So I thought I’d just add some fuel to the fire and give my readers some overall guidelines about mast cell tumors and chemotherapy.
As many already know, these cancers come in different grades (1, 2 and 3). Grade 1 are almost always benign, grade 2 are intermediate (some benign and some malignant) and grade 3 are universally malignant.
Your vet will give you the grade following receipt of the biopsy report, which is completed by a path lab after submission of tissue from the tumor.
Wide excision (removal of a large swath of normal-appearing tissue around the tumor) cures many mast cell tumors. Pretty much all grade 1, and about 90% or so of grade 2 mast cell tumors are gone permanently after wide excision. Grade 3 mast cell tumors are candidates for chemo and possibly radiation and more as they will often come back and spread even after surgery.
The tricky guys are those grade 2 mast cell tumors. Since some behave like benign tumors and some like real cancers, what are we supposed to do?
Well, the key is in getting more information about your dog’s individual tumor. There are a couple of bits of information that are valuable that can help you predict the behavior of your dog’s grade 2 mast cell tumor.
The single most important one is called the mitotic index. This is the number of cells that are actually dividing seen by the pathologist under the microscope.
The magical cut off is somewhere around 5. This means that if the tumor has a mitotic index of less than 5, it usually will behave less aggressively and in my opinion do not require surgery, as long as you have clean margins on the removed tumor.
More than 5? We need to now consider hitting these guys with the full spectrum approach (diet, supplements, chemo, and other strategies discussed in The Dog Cancer Survival Guide).
You may read about other markers (kit, AgNORs, Ki67) but these are much less useful than mitotic index. If the mitotic index is around 5 though, consider these other markers for more data.
By the way, not all vets may know about this stuff, so remember to be your dogs primary health care advocate and speak up! You vet is the one who has to order this testing of the biopsy specimen from your dog.
The squeaky wheel gets the oil!
Best to all,
Dr D
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Dear Dr. Dressler:
I recently adopted a 7 year old rescue dog (Wiemeraner/Lab mix) with Diabetes and Thyroid Desease, both are now under control with proper exercise and diet and medication. I discovered a swelling on her front leg and a smaller swelling on the back thigh, they looked completely different from each other. I took her to my vet, he said it wasn’t swollen and no idea what it was. A few weeks later it happened again in both area’s and I took her to another vet who said they were Mast Cell tumors. I called the rescue group and found she had a grade 2 tumor removed 8 month’s ago on the front leg and this was a recurrence, and another removed from her belly which now has also recurred plus the new one on her thigh, and since have found numerous more small ones. I had some asperated and 1 out of 3 came back positive, so my vet sent me to an Oncologist. The Oncolgist has diagnosed her with Cutaneous Mastocytosis and said she has 3 to 6 months to live. She does not recommend surgery as there are so many tumors and the larger recurrence on her front leg removed last year and could only get 1mm margins (clean) but there is not enough tissue to work with and the muscle would be very damaged trying to remove it again, the leg would be useless. So Chemo has been recommended 8 treatments and then inhibtors there after. My question is, is this a reasonable thing to do for her. She is not in pain, has been on Benedryl and Pepcid 2 weeks now (ordered by our vet) but with her Diabetes and other heath issues I am unsure of what is the best course of action for her??? Any advice would be appreciated. Jen
Dear Jennifer,
you need to do a treatment plan analysis as is discussed in the Guide. Get an idea of side effect frequency, side effect severity, what the life quality negatives are with treatment, what are the odds of a response given the recommended treatment, and what is the added life expectancy (median, like an average) with the treatment. Once you obtain this specific information from your oncologist your decision will clarify.
Best,
Dr D
Dear Jess,
Sorry to hear this- sounds very hard.
if the drug is not working discuss discontinuing it with your oncologist. You might also consider Neoplasene at this stage. I hope this helps,
Best,
Dr D
Dear Dr. D,
I have a 4 year old Boston that just recently had two mast cell tumors removed from his hind leg. They were fairly small and close to each other so only one incision. One of the tumors came back after biopsy as a Grade I, the other was diagnosed as a Grade 2. In reading the reports of the biopsy, the findings say similar things for both “Nulcie are pleomorphic with scattered chromatin and a low (<1 mitotic figure per 10 hpf) mitotic index". The comments on the Grade 2 tumor are more extensive. I'm wondering is it possible for a Grade 1 and 2 tumor to have similar mitotic figures? The recommendation from my vet was to see an oncologist. Should I have cause for concern?
Dear Clarrisa,
i too would see an oncologist, especially if your vet is recommending it. This tells you that your vet is suggesting more expert advice, and if your vet is telling you this, I feel it is sensible wisdom. There are more aspects of a pathology report than mitotic figures, and there are other determinants of tumor behavior as well. However, right off the bat, I have cautious optimism that things will be okay. But it is important to follow your vet’s advice. I hope you are also using the other steps to help your dog? Diet, apoptogens, immune support, and the rest of the steps in the Guide??
Best,
Dr D
Hi Dr. Dressler,
My 8 1/2 year old mixed breed dog had a stage 2 mast cell tumor removed from his hind leg about two months ago. The incision site took several weeks to heal; it kept ripping open and having to be re-stitched. The lab said the removal had incomplete margins. My vet sent me to an oncologist and we had a tumor marker test done that came back with a 65 reading (I’m not sure what this means exactly, but apparently over 54 is likely to metastasize). The oncologist is recommending localized radiation as well as chemotherapy asap.
I’m not sure yet what myself, my wallet, and most importantly my dog can handle. While I understand nothing is 100%, I am trying to weigh the potential of a successful outcome with the negatives.
What I cannot seem to understand is this: Since the radiation will have been delayed so long due to the difficult healing, is it still nearly as effective?
Also, how much should I take the tumor marker results to heart?
Thank you for any input in this confusing time,
Julia
Dear Farokh
I am sorry to hear about this.
You need to get the biopsy report back before surgery. There is risk of spread, and the type of cancer helps tell us where to look for the spread before doing major surgery. This is not your question, but is your next step nonetheless. The ulnar resection is possible but the problem is you will not likely remove the cancer cells with it. Thus you would need to diet your dog and help your Buddy up the stairs…not an easy answer I am afraid but it is doable.
I hope this helps
D
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