When to Avoid Chemo for Canine Mast Cell Tumors?
Dr. Demian Dressler is internationally recognized as “the dog cancer vet” because of his innovations in the field of dog cancer management, and the popularity of his blog here at Dog Cancer Blog. The owner of South Shore Veterinary Care, a full-service veterinary hospital in Maui, Hawaii, Dr. Dressler studied Animal Physiology and received a Bachelor of Science degree from the University of California at Davis before earning his Doctorate in Veterinary Medicine from Cornell University. After practicing at Killewald Animal Hospital in Amherst, New York, he returned to his home state, Hawaii, to practice at the East Honolulu Pet Hospital before heading home to Maui to open his own hospital. Dr. Dressler consults both dog lovers and veterinary professionals, and is sought after as a speaker on topics ranging from the links between lifestyle choices and disease, nutrition and cancer, and animal ethics. His television appearances include “Ask the Vet” segments on local news programs. He is the author of The Dog Cancer Survival Guide: Full Spectrum Treatments to Optimize Your Dog’s Life Quality and Longevity. He is a member of the American Veterinary Medical Association, the Hawaii Veterinary Medical Association, the American Association of Avian Veterinarians, the National Animal Supplement Council and CORE (Comparative Orthopedic Research Evaluation). He is also an advisory board member for Pacific Primate Sanctuary.
Updated: June 19th, 2019
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
Dr. Demian Dressler is internationally recognized as “the dog cancer vet” because of his innovations in the field of dog cancer management, and the popularity of his blog here at Dog Cancer Blog. The owner of South Shore Veterinary Care, a full-service veterinary hospital in Maui, Hawaii, Dr. Dressler studied Animal Physiology and received a Bachelor of Science degree from the University of California at Davis before earning his Doctorate in Veterinary Medicine from Cornell University. After practicing at Killewald Animal Hospital in Amherst, New York, he returned to his home state, Hawaii, to practice at the East Honolulu Pet Hospital before heading home to Maui to open his own hospital. Dr. Dressler consults both dog lovers and veterinary professionals, and is sought after as a speaker on topics ranging from the links between lifestyle choices and disease, nutrition and cancer, and animal ethics. His television appearances include “Ask the Vet” segments on local news programs. He is the author of The Dog Cancer Survival Guide: Full Spectrum Treatments to Optimize Your Dog’s Life Quality and Longevity. He is a member of the American Veterinary Medical Association, the Hawaii Veterinary Medical Association, the American Association of Avian Veterinarians, the National Animal Supplement Council and CORE (Comparative Orthopedic Research Evaluation). He is also an advisory board member for Pacific Primate Sanctuary.
Dr. Dressler,
Thank you for this informative site, I will be looking to purchase the survival guide. My 4 year old mini dachshund developed a lump on the top of her left front paw, it seemed like the area arose overnight. I brush her regularly and she goes to a groomer and neither of us had noticed it. Our local vet was unable to draw any fluid from the growth and surgically removed it. We were called last night and told it is a Grade 2 mast cell tumor, with “low mitotic index” – no number given.
The neoplastic cells extend to the margin per the phone report. I plan to get a copy of the report. We have an appointment next week with an oncologist. Our local doctor did not recommend anything in the mean time. What are your overall thoughts? Thank you so much.
Dear Jan,
Get a wide excision scheduled as soon as possible. Although spread is not hugely likely, try to get complete blood work, a urine test, and an ultrasound of the abdomen done before this to make sure there is not obvious spread before putting your dog through another surgery. Change to the dog cancer diet in the Guide (and the rest of the plan) and get your Apocaps to start 10 days post op.
Best of luck,
Dr D
Dr. Dressler,
Hi. Thank you for your very informative site.
We have a 8 year old previously healthy Basenji who was diagnosed w/ grade 2 MCT, low mitotic index in the proximal aspect of her upper limb (FR leg). No mets. Resecetion was done: grossly normal margins but ditry margins microscopically and given the location, the surgeon felt they couldnt go wider.
Our vet discussed RT, which is not done in our state (UT) but could be done in CO. We met w/ an oncologists who felt we’d have very good odds w/ Masitinib as a first line thereapy post-op.
What do you think? They inidcated a better than even chance of no recurrance and in the case of a local recurrance, the option of RT would still be feasible (though Ive read those recurrant tumors can change grade and be more malignant and aggressive)
Ive had a hard time getting numbers for mastinib in this type of case (limb, resection w/ microscopic dirty margins Grade 2).
Seems hard to predict those grade 2’s, but is this a a reonabale approach? Try Mastinib and if any recurrance, go to RT (assuming we have the option). Or is it too risky and RT a better option by far (which my wife is less enthusiastic about).
Thank you.
Gary
Dear Dr. Dressler,
Thank you for your reply. When it comes to fish, is it ok to use fish oil in her diet?
thanks
Russ
Oops! I should have said — over 50 tumors removed since September of 2005.
Thanks
Dear Dr. Dressler
Lola, my four-legged companion has had over 50 tumors removed since September of last year. Lola has been with me for nine years at the end of April. I assume Lola to be at least eleven or twelve years of age since she was a stray.
When I brought Lola into my home, she had two bumps on her. The dermatology vet hospital where I took Lola, told me to ignore the bumps because the bumps were nothing more than fat tumors. The dermatology clinic owners have a monopoly of dermatologists in southern California, Hawaii and other locations. So, getting a second opinion is impossible. Instead they put Lola through all kinds of allergy tests because she had terrible allergy problems. Not once did they mention the use of Benadryl.
Three and half years later, one of the two bumps changed colors. I knew something wasn’t right. I took her to a vet hospital to it aspirated. The bump Came back positive and the two tumors plus a third were removed. All grade 2, level 1. Had the dermatology clinic performed their job as they should have, I would’ve taken a complete different path for Lola’s health.
First of all, I wouldn’t have allowed all those various vaccines to be given to her. It wasn’t until after the fact that I learned all those vaccines are not good because of the potential diseases they can produce. I would’ve taken a more holistic approach to her diet as I now do, and eliminated many of the drugs I believe have caused her immune system to be challenged.
Recently, six active tumors were injected with a very small dose of steroid. Since Lola’s system is very sensitive, the oncologist said the amount given is far below what is normal for a dog her size and weight. Lola does react well to the small dosages.
Now I am at a cross roads of what to do. The oncologist suggested a chemo drug (the generic version) as a pill to give her. I’ve resisted this because I am frightened by the potential side affects. What do you think?
Sincerely,
Russ
Dear Russ,
I am sure the decision not to pursue surgical removal has been thoroughly discussed? The vast majority of Grad 2 mast cell tumors can be removed with a wide excision surgery (yes, even old dogs) as long as it has not spread already.
You need to decide what your priorities are by defining your own values. Life quality or life quantity? This is discussed in detail in the Guide. In the realm of conventional cancer care, if life quantity goes up, life quality risks go up too. I assume you have information about diet?
https://www.dogcancerblog.com/blog/diet-for-dogs-with-mast-cell-tumors/
Also you want to stabilize any mast cells in the body and deal with histamine:
https://www.dogcancerblog.com/blog/mast-cells-and-luteolin-in-cancer-treatment-part-1/
of course I am partial to the supplement that I use in my patients that contains luteolin 🙂
You need this info:
https://www.dogcancerblog.com/blog/dog-cancer-decisions-in-the-gray-zone/
and
https://www.dogcancerblog.com/blog/mast-cell-tumors-in-dogs-some-advances-in-conventional-care/
also you may want to have your vet call Dr. Ahn at AB sciences in New Jersey to access masitinib, a pre-FDA approval drug that may help.
Best,
DR D
Hi Dr. D,
I just read this article and was hoping you could comment. My dog’s mast cell tumor had a mitotic rate of 0-1 when staged back in Sept. It was excised, with narrow margins the first time and came back in 2 weeks, so the vet did it again and got wide margins, again with 0-1 MR. The tumor came back again and we were referred to http://www.fvs.com They have given him every chemo drug in the book(vinblastine, palladia, lumostine) and he has not responded at all. His lymph node was the size of a tennis ball. The oncologist gave us a drug from Europe(I don’t remember the name). It shrunk the lymph node by half but that was all.
I was hoping you could comment on how this tumor is so aggressive with a mitotic rate of 0-1. Nothing we do works. Also, if you have any advice on any other options, it would be greatly appreciated. For your info, Kramer is a 11 y.o. Weim/Greyhound mix.
BTW, Got the book and thought it is very well done.
Thank you very much for your time.
Dear Todd,
the Grade of the mast cell tumor is the first thing that predicts behavior. Mitotic index is a second level predictor once the grade is established and is most useful for Grade 2 (intermediate grade) mast cell tumors where you don’t know if it will behave aggressively or not. Then we look at mitotic index and some other things to try to predict behavior.
I hope this helps
Dr D
fyi..i just purchase paladia from my vet for $220 for 30 pills for my schnauzer
Dr. D,
Our 5yr old Great Dane/Lab mix recently had a tumor roughly the size of a walnut removed from the back of her leg. The pathology came back as Grade I mast cell tumor, with a mitotic index of 0-1. However she has 3 other smaller growths the size of a pea in other surgically aceptable areas.
My question is are we likely to have ongoing tumors appear and what is the prognosis if we continue to see new tumors. Can we expect to have all of these sucessfully removed thru surgury given her pathology or is her outlook likely to deteriorate over time.
My vet seams optomistic but we don’t want to be caught of guard given this may not be the only malignant tumor.
Dr. Dressler, I just found out that my English Bulldog, 7 years old, has a poorly differentiated Grade III mast cell tumor. The biopsy report said the “mast cell tumor appears completely excised.” However, it says her mitotic index is 6/10. How bad is that number? Thank you very much.
Gary
Dear Gary,
you need to understand this is a very serious cancer. The statistics are rather dreadful: less than 2 month survival time for a grade 3 mast cell tumor with a mitotic index of greater than 5. I would consider the whole arsenal in a 7 year old Eglish Bulldog, depending on what type of person you are (how risk averse). I would utilize the full range of surgery, chemo, possibly radiation (the latter two under oncologist supervision), as well diet, supplements, life quality measures etc. that I describe in the Dog Cancer Survival Guide. You should also pay close attention to the treatment plan analysis portion of the book due to the grim numbers involved in cases like your dog’s, to make sure that what you do makes sense to you and feels right from an ethical standpoint.
Dr D
Thanks for the informative information – I enjoyed reading it! I always enjoy this blog. 🙂 Cheers,