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.
I have a 16 year old cocker who had been diagnosed most recently with kidney failure in march 2010. She also had a nasty e coli infection that kept muating through several drugs and we finally conquered it with sub q injections of meripenem, which she is still on. She has a hx of bladder stones, IMTP, and chronic IND – she has also had pancreatitis in the past as well as vestibular. She is a very spunky girl. Two weeks ago she awoke with a huge lump just above her anal gland. it was purple. I took her to the regular vet and they tried to express the anal glans, which made it worse. Then they did a needle aspirate and she bled for two days. I took her into the specialist who had been seeing her for the kidneys and he diagnosed a mast cell from a bood sample. Due to her age and condition her recommended tricolsane (sp?) injections – she was put under for a couple of minutes. The first treament resulted in the tumor shrinking and she was up and about and a little piggy. The second treatment a week ago seemed to leave her very lethargic and her rear legs are very weak – weaker than they were before. She walks for a short distance and then she slowly sinks to a sitting position. Her appetite is still good but she tires very easily.The specialist wants to put her on Paladia but my gut feeling is it will do more harm than good – she has always had chronic IBD – so much so that if you change her food at all, even to a bland chicken and rice mix she gets bloody diarhea with frank blood for days. Right now she is on Royal Canin canned Renal LP modified mixed with cream of wheat, baby sweet potato, baby turkey and Cranimal powder, Do you have any stats or research on Paladia and kidney dogs or dogs with IBD. She takes 1 mg pred 2 x a day (has for years for her immune issues), 1 mg thyroxine 2x day, 1 pepcid 2x a day, a meripenem injection 2x a day, 100-200 ml lactated ringers sub q per day and 4 ml aluminum hydroxide liquid after each meal. She is also on 1/2 benadryl 2x a day. She weighe 20 lbs. She is my family and the light of my life. I rescued her on new years eve 2004 – they said she was 10 years old and she was blind and partially deaf. What supplements can I give her with the kidney issue and how can I slowly adjust her diet to help with the cancer?
Dear Judy,
this sounds very hard for everyone. Tricky stuff here. No stats I know of to answer this question. I’d have your oncologist contact Dr. Ahn at AB Science to see if you can get Masitinib under the compassionate use program.
Yes, lots of supplements. Have you read the Guide? An easy read and I believe you will find a lot of useful information. As to the kidneys themselves, I’d be using Azodyl as a minimum, of course all under veterinary supervision.
Hope this helps,
D
We took the spleen out two days ago on the theory that if the mass were malignant (MCT or otherwize), it needed to come out; and if it were benign, well then at least we would know that and wouldn’t have to worry…and who knows, maybe by taking his spleen at 5 we will prevent him from getting a hemangiosarcoma at 8. (We lost another Golden 3 years ago to that nightmare.)
The path report came back today as benign nodular hyperplasia, so needless to say we are delighted!!! Some might argue we took his spleen out unnecessarily, but I would not be one of them.
With the risk to Goldens being as high as it is, especially for hemangiosarcoma, I almost wonder if a preventative splenectomy at age 5 wouldn’t be a good idea. (Unfortunately, many might not be able to afford it.) Thanks for your input.
Great news doc!
Stay in touch
Best,
D
Our 5 year old golden retriever had a 1cm mast cell tumor removed from his left hip area two weeks ago. The lump had been there for two months but had not changed in size at all in that time and he had no systemic symptoms. The bad news was that the tumor was a grade 2 but the good news was that the mitotic index was 0 and there were 7 mm clean margins all around the mass (10mm might have been better but 7mm wasn’t bad). We were actually feeling pretty good about the prospects of a surgical cure until a spleen ultrasound yesterday showed a 2cm hypoechoic mass in his spleen. The question I guess is whether this is a metastatic lesion from the mast cell tumor, a new and different primary malignancy, or a coincidental benign tumor. (I almost wish now we stopped at the Mitotic Index of 0 and hadn’t done the ultrasound.) So my question is this…what next? Do we watch the mass and just re-image it in 4 weeks, do we needle biopsy it and run the risk of associated bleeding and a possible second anesthesia to remove the spleen if the biopsy is bad, or do we just bite the bullet now and remove the spleen without a biopsy beforehand. He’s only 5!!! (I’m a pediatrician myself so I am medically sophisticated in the human world.)
Dear Dr Steve,
As you know we don’t know the nature of the mass without cytology or biopsy. Statistics these days point to 75% of Goldens ending up with cancer. If this were my dog I’d explore the abdomen and biopsy. Yes, could be benign, or a hematoma, or something else, but assuming all other testing is normal we just don’t know, and mast cell tumors sometimes don’t read the book. I’d rather have a diagnostic surgery than do nothing. My two cents…
D
My 8 year old Rhodesian Ridgeback just had an MCT removed from an area just behind is right front armpit. The biopsy came back as Grade III with MI of 18. Chest X-rays and abdominal ultrasound show no organ tumors at this time. The vet has advised a course of Vinblastine and Prednisone.
Based on my research, the avg life expectancy for a Grade 3 / MI 18 tumor is three months even though he shows no other symptoms at this point. Would you still recommend proceeding with the chemo? Not knowing much about the mastineb, would this be a better approach?
I have just purchased your book and looking forward to learning more. Thank you.
Is the wide excision surgery ALWAYS advisable? My dog Wally just had a mast cell tumor removed from a few inches above his penis. It is Grade 2. Wally is approximately 11-12 years old. I do not yet know what the mitotic index indicates, but if it shows below 5, for quality-of-life reasons, would you endorse not doing the wide excision? It seems that if the index is low, the likelihood of spread is low, so why put the dog through that second surgery. If the index is high, again, why put the dog through it? Thank you for any advice.
Hi Dr.,
My pit bull/rotti mix just had a MCT on her front limb removed. It came back as a grade 2 and the vet says that because of location, they were not able to get a good amount of margins around the tumor. All blood tests, x rays, and buffy coat came back clear. She is 11 years old and the MCT was removed about 1 week after I noticed her licking at her leg and noticed the tumor. Is radiation the answer? Or are medications a better choice? The vet told me radiation will cost me about $10,000 and I can try to do something to get that money but as of right now I do not have it. My dog is my best friend and I will do whatever is necessary, someway somehow. Thanks in advance.
Jaime
Dear Jamie,
first you need to find out the mitotic index. This tells you how aggressive these gray zone cancers are. Read this post. Ultrasound is the imaging of choice if you were to pick one to assess spread of mast cell tumors. You might want to get an oncologist involved here! If no spread and regrowth is occurring as a last resort, ranother option is removal of the affected limb. Here is more info on that, (focusing on bone cancer but the gist is the same). Other steps I would be taking here are Apocaps, diet change, supplements to help slow metastasis, benadryl, cimetidine, consideration of masitinib (check into the compassionate use program at AB Sciences in New Jersey), brain chemistry modulation to a cancer fighting state, and more. Please take some time to get and read the Guide– I think it will help you. Remember to have all steps supervised by your vet/oncologist.
Best,
D
I have a 18-month old Chihuahua-Labrador mix. About 6 weeks ago a 2 cm tumor appeared out of the blue on her right front leg. It was removed but the vet was not able to get much margin because of the location of the tumor. The tumor was not encapsulated and there were mast cells in the margins they were able to remove. It was diagnosed as MCT Grade II with a mitotic index of 2 and I was referred to an oncologist. She presented me with 4 options: watch and wait, conventional chemo (Vinblastine and Lomustine), Masitinib and radiation. I’m in a complete quandry on what to do.
DR. DRESSLER,
I FORGOT TO MENTION THAT THE NODULE WAS REMOVED FROM THE TAIL, ABOUT UPPER MID SECTION.
DIANA
DEAR DR. DRESSLER,
MY FOUR YEAR EIGHT MONTHS OLD TOY MANCHASTER TERRIER GOT A SMALL WART REMOVED THAT HE HAD FOR 1 -2 YEARS. THERE WAS NO CHANGE IN SIZE OR COLOR AND EVERYONE THOUGHT IT IS JUST A WART AND HARMLESS.
MY INSTINCT TOLD ME TO HAVE IT REMOVED LAST WEEK, WITHOUT ANY DIRECT REASON. THE DOG WAS NOT LOSING WEIGHT. HE IS AN INCREDIBLE EATER AND RUNS 2-4 HOURS A DAY. HE ACTUALLY GAINED 1,5 POUNDS, WHICH WORRIED ME (HE IS 13,6 POUNDS). WE FEED HIM A RAW DIET, HE GETS CHINESE SUPPLEMENTS AND VITAMINS AND MINERALS AS WELL AS LIQUID SHARK CARTLIDGE. HE IS VERY ACTIVE AND WE ARE DOING A COMPLETE BLOOD CHECK WITH TITERS ONCE A YEAR (WAS JUST DONE 6 MONTHS AGO).
THE BIOPSY HOWEVER CAME BACK AS A GRADE ONE MAST CELL TUMOR AND I AM DEVASTATED. WE HAVE AN APPOINTMENT WITH AN ONCOLOGIST ON MONDAY I AM TRYING TO FIND SOME SPECIALTY LABS IN THE LOS ANGELES AREA TO HAVE THE NODULE REEXAMINED IN DIFFERENT LABS, AS I DON’T REALLY TRUST THE PLACE THAT HAS DONE THE BIOPSY IN ARIZONA.
HERE IS HOW THE REPORT READS:
EPIDERMIS SHOWS MILD ACANTHOSIS, MILD PIGMENTATION, MODERATE LOOSE ORTHOKERATOSIS. HAIR FOLLICES ARE MIXED ANAGEN AND HAIRED TELOGEN WITH MILD LUMINAL KERATOSIS. SEBACEOUS GLANDS ARE NORMAL. DERMIS CONTAINS SMALL SLIGHTY RAISED AND MILDLY CIRCUMSCRIBED SUPERFICIAL PROLIFERATION OF SMALL MODERATELY WELL DIFFERENTIATED NEOPLASTIC MAST CELLS, MIXED WITH SCATTERED EOSINOPHILS SURROUNDING A FEW ADNEXA. SURROUNDING DERMIS HAS MILD PIGMENT INCONTINENCE AROUND THE BULBS OF A FEW FOLLICLES.
TUMOR IS SUPERFICIAL AN APPEARS TO BE ADEQUATELY EXCISED. PROGNOSIS IS CONSIDERED FAVORABLE, FOOLO UP AND REEAMS ARE RECOMMENDED
PLEASE LET ME KNOW WHAT I CAN DO TO PREVENT ANY FURTHER MAST CELL GROWTH. I STILL DON’T UNDERSTAND HOW ALLERGIES OR INFECTIONS ARE RELATED TO A GROWTH OF A MAST CELL TUMOR. IS HIS IMMUNE SYSTEM TOO WEAK OR TOO STRONG TO ALOW THAT. HE NEVER HAD ALLERGIES OR ANY INFECTIONS I KNOW OF. PLEASE DOC LET ME KNOW HOW SERIS THIS IS. THE LITTLE BOY IS MY LIFE AND I AM HAVING A NERVOUS BREAK DOWN.
THANKS,
DIANA
Hi Dr. Dressler,
I just stumbled across your site after searching for information on canine mast cell tumors. My 10 yr old whippet/lab/terrier mix Keko was diagnosed this week (via aspirate) with a mast cell tumor on his right front leg, a couple inches below the elbow joint. We have done radiographs of the chest and abdomen and an abdominal US, all came back clean.
Due to the location of the tumor on my dog’s very thin front arm (approx 7 cm in diameter at the location of the tumor), it seems highly unlikely that an excision could be accomplished that will yield clean margins without resorting to an amputation. My vet and one oncologist who has been consulted are also reluctant to do a punch biopsy because of the risk of dumping all those angry cells into Keko’s system. We are therefore looking at amputation of the front limb as one option for treatment; however it seems we would be taking this (drastic) measure without being able to grade/stage the tumor or determine the mitotic index. Am I thinking of this correctly? Are there other ways to get this information (like from another aspirate – and would that pose risk similar to a punch biopsy)? Any other data we could use to help us know how aggressive this tumor is?
It would seem a shame to remove Keko’s leg for what might turn out to be only a Grade/Stage 1 tumor.
Many thanks,
Keko’s family in Hawaii