The Oncologist’s thoughts on mast cell tumors
Sue Ettinger, DVM. Dip. ACVIM (Oncology). Dr. Sue is a boarded veterinary medical cancer specialist. As a Diplomate of the American College of Veterinary Internal Medicine (Oncology), she is one of approximately 400 board-certified veterinary specialists in medical oncology in North America. She is a book author, radio co-host, and an advocate of early cancer detection and raising cancer awareness. Along with Dr. Demian Dressler, Dr. Sue is the co-author of The Dog Cancer Survival Guide: Full Spectrum Treatments to Optimize Your Dog’s Life Quality and Longevity.
Updated: November 22nd, 2018
If ever there was a tumor that fits the saying: “one size does NOT fit all”, it is mast cell tumors (MCT). These tumors are common, particularly skin tumors, in dogs. You may know a dog that had a mast cell tumor removed with surgery and went on to live many happy years to never hear from the MCT again. On the other end of the spectrum, you may know a dog with an aggressive MCT that recurred and/or metastasized quickly and lived just a few months.
What gives? Why is there so much variation in outcome? If your dog has a MCT, will it be a “good” MCT or a “bad” MCT? Can that be predicted? Why is there a new grading system? Do the new c-kit inhibitors (Palladia and Kinavet) work? In my next series of blogs, I hope to answer many questions about the complicated mast cell tumor.
First, let’s understand what MCT are. Normal mast cells are a type of immune system cell and play an important role in inflammation. While other immune system cells tend to circulate throughout the body, mast cells don’t – once they mature, they take up residence in specific tissues. While they can be found anywhere, many live in tissues that mark the boundary between the outside and internal environments; for example, the skin, the mouth, the digestive tract, the nasal passages, and the lungs.
Mast cells hold structures inside their cell walls called granules, which are like little sacks. The granules are filled with substances, or cytokines, including heparin and histamine, which help the immune system respond to problems. Heparin is a blood thinner which helps defend the body against foreign invaders, and histamine is a chemical that triggers inflammation. Normal mast cells release these substances when prompted by the immune system. In addition to their role in inflammation, mast cells are involved in allergies, anaphylaxis (systemic inflammation), the healing of wounds, and defense against outside pathogens.
In this seminar, Dr. Dressler addresses a number of important topics on Mast Cell Tumors, so be sure to get your copy for more information!
Mast cell tumors are cancerous accumulations of mast cells with a malignant potential. MCT is very rarely found in humans, but it is the most common malignant skin tumor in dogs, accounting for 15-20% of all skin tumors. Mast cell tumors first occur in the skin and the subcutaneous tissues beneath the skin. It’s very rare to find MCT in internal organs without a primary skin tumor, but skin tumors can spread to the regional lymph nodes, the spleen, the liver, other places deep in the abdomen, and to the bone marrow.
What causes MCT? Like most tumors, the exact cause is not known. About one-third of dogs have a genetic mutation in a protein called the c-kit oncogene. Unlike skin cancer in humans, which is often associated with sun exposure, studies have found no link between sun exposure and MCT in dogs. But chronic inflammation of the skin may predispose dogs to develop MCT, as can the repeated application of skin irritants.
We also tend to see it more commonly in the following breeds: Boxers, Boston Terriers, Labradors, Golden Retrievers, Pugs, and Staffordshire Bull Terriers. Boxers tend to develop low and intermediate grade tumors.
MCT are one of the most common tumors I see in my oncology practice at the Animal Specialty Center. When should you see an oncologist for MCT? We will pick up there at my next post. In the meantime, remember there is a lot more information about MCT in the Guide.
Get the book to read more on Mast Cell Tumors from an Oncologists Perspective!
Sue Ettinger, DVM. Dip. ACVIM (Oncology). Dr. Sue is a boarded veterinary medical cancer specialist. As a Diplomate of the American College of Veterinary Internal Medicine (Oncology), she is one of approximately 400 board-certified veterinary specialists in medical oncology in North America. She is a book author, radio co-host, and an advocate of early cancer detection and raising cancer awareness. Along with Dr. Demian Dressler, Dr. Sue is the co-author of The Dog Cancer Survival Guide: Full Spectrum Treatments to Optimize Your Dog’s Life Quality and Longevity.
We have now seen the oncologist. Ultrasound showed mass on spleen and liver, but no mast cells. Lab on spleen mass came back as a common non-cancerous growth. The liver mass–reported as small, but I don’t know what size–is likely a recurrence of the hepatocellular carcinoma, and is likely the reason for the elevated liver enzymes. The grade 3 MCT removed from her ear had a MI of 17. The margins were clean but a very, very slim 1 mm in some areas. The oncologist would like to go back and do a full ear canal ablation, and is recommending Palladia for life. Is there ever a time when surgical removal of a grade 3 mct is curative? In reading about it, Palladia is almost as scary sounding as the cancer itself.
It’s October 18, 2013. I recently purchased the e-edition and I have read the Guide on Mast Cell Tumors. Since information is continually changing and evolving I think its important to address new updates rather then refer us to the Guide. The book is essential and has helped me cope among other things. Since you wrote the book and it was published what new updates do you have about…
a) Mitotic Index- you quote in the book that these numbers will certainly be refined. Have they been?
b) there seems to be a question about Krill vs. Fish Oil. The Pure Gold comments from a year ago come to mind. Have your thoughts and studies changed on this subject?
c) I don’t see the new Blog that you speak of with regard to Palladia and Kinavet. The Guide refers to these C-kit inhibitors, but again the book was written and published a while back. What are the new updates and test results on these inhibitors?
Is there anything new out there that Guardians should know about? You and your team are cutting edge. Guardians like me count on you to educate us so that we can speak intelligently to Oncologists and Vets alike. Please update me as soon as possible. DaisyMae had surgery for MCT (4) and Lymph node removal She is doing great No symptoms at all. Prognosis is hopeful,
BUT the fight against cancer begins!
I wish I could afford Apocaps…Would it be wise to lesson the amount you suggest rather then not buy it at all. Daisy is 83 Lbs
Dear dr Ettinger,
My cattle dog mix has been diagnosed with a stage II mast cell tumor. Because it is deep in her dorsal neck muscles, tthe vet Did not get clean margins. He did not want to cause her muscle damage.
She has one mitosis per 10 on the mitotic index . Further surgery to seek clean margins does not seem o be an option.
Any advice would be appreciated. I am waiting to get her in to see an oncologist.
Many thanks.
My 13 yr old Siberian husky was diagnosed with a grade 3 mass cell tumor. Mitotic rate 2-4/ hpf. The tumor has been romoved with clean margins of 1 -1.5 cm. she has been taking prednisone daily and vinablastine once a week . I have consulted with 3 oncologists ,all have a different opinion . one has suggested radiation 5 times per week for four weeks even with the clean margins . Another oncologist has suggested adding palladia during the treatment of prednisone and vinablastine . He says this is a very agressive tumor and needs the combination of the 3 drugs . The other oncologist wants to use the vinablastine and prednisone and save the palladia for when the cancer returns . Please help any advise would be appreciated
Hi!
Our American Bulldog was just diagnosed with a grade 2 mast cell tumor. The report says the tumor extends to the deep surgical cut margin, does this mean the cells are still in his body? It also says the skin specimen contains an infiltrative neoplasm composed of atypical mast cells and eosinophils. Mitotic figures are not seen in 10 HPFs. What does this mean? Thanks so much!
Jennifer,
The biopsy report indicated that the margins are incomplete, and for MCT that means recurrence is more likely than if the margins are clean and wide. You should consider an consult to determine if a scar revision is an option, or to consider radiation, which is very effective for incompletely resected grade 2 MCT. As for the mitotic figures, check out my recent posts, and good luck!
https://www.dogcancerblog.com/blog/all-about-mast-cell-tumor-grade/
https://www.dogcancerblog.com/blog/beyond-mast-cell-tumor-grade-other-prognostic-factors/
https://www.dogcancerblog.com/blog/mast-cell-tumor-treatment-surgery-and-radiation/
All my best, Dr Sue
[…] spent a number of recent blogs understanding how MCT behave, how to confirm the diagnosis, MCT grade, what staging tests to consider, and what the prognostic […]
My dog was first diagnosed with mast grade 2 four and half yrs ago. Last week he had a second tumor removed from the exact same location this came back grade 3 with mitotic index of 24 per 10 hpfs. He will be 8 in feb 2013 I am not sure what to do next please any ideas will help I have been thru so much with this dog he almost died at 10 months and we thought we beat the cancer now after 4 and half yrs it’s back and grade has moved from 2 to 3
Amy, Please read the series on MCT, and most importantly see an oncologist. Unfortunately tumors can jump to higher grades. Your dog shoulb be tested for metastasis (staging) and chemotherapy should be considered.
Good luck. Remember, this is a treatable cancer, and there are options.
https://www.dogcancerblog.com/blog/all-about-mast-cell-tumor-grade/
https://www.dogcancerblog.com/blog/beyond-mast-cell-tumor-grade-other-prognostic-factors/
https://www.dogcancerblog.com/blog/mact-cell-tumor-treatment-chemotherapy/
All my best, Dr Sue
Dear Dr.,
I hope you enjoyed your Thanksgiving! I am writing with questions feeling a bit lost. Three weeks ago my recently-turned 6-year-old, Saint Bernard, Tango, had 2-4 raised bumps on his back haunch. He’s a very in shape and healthy pooch..daily walks and weighs 115 pounds. The bumps were about the size of a quarter each. They happened instantaneously as the night before he was being petted all over and there was no lumpiness or bumps. Now the bumps just appear as raised fur and are definately below the fur. Anyway, I had my husband take him to the vet the next day because more bumps appeared along his back haunch and his left lymph node became the size of a baseball. It was huge. The vet said we’ll put him on prednisone for 3 days–it’s probably a hive reaction. 5 days later I am not believing in the vet’s diagnosis and I get online to find all of this information on MCT. His bumps would go up and down on size at any given time and his lymph node had shrunk but now the pred prescription was gone and the bumps seemed more, along with a growing lymph again. I set another appt. and again hubby took him (I’m not able to during the week due to my 7:30-5:30 work schedule). They tried getting blood and once they did they said his CBC came back fine. They aspirated the lymph and called to say they found bacteria in it so he must have an ear infection draining into the lymph and causing a hive reaction in the body. They do not run pathology on any of the aspirates they do–just look under a slide (it’s a smalltown NW Iowa vet). Anyway, it had been 2 weeks now….they put him on cephalexon, mometemax (ear infection) and prednisone again. Now forward to yesterday. Tango has an obvious fever, not eating or drinking and not wanting a daily walk. He looks sad and breathing is irregular. I call the vet yesterday morning-the bumps on the back of his body have gone down in size but are everywhere except on his stomach, privates, ears, or legs…the lymph is still somewhat enlarged (egg size) and now pea-sized bumps are along his sides of his ribs, his top of his head & cheek, he appears sad. Also a newly developed bump/tumor on his right shoulder is the size of an egg. It’s Saturday so I take him to the vet. I talk to the vet in lenghth about the histamine reaction/imitation that MCT’s also have so perhaps was the hives diagnosis incorrect and could it be a mast cell tumor? I want to know, does he have cancer? I just had to put my sweet 9 year old pup, Mannie down 6 months ago a day after he received his cancer diagnosis–xrays showed tumors all over his body. I have to be prepared and helpful to my pooch. The vet doesn’t know that much details about MCT (he practices on cows, pigs, horses, dogs, cats, etc..not small animal specialty) and admits it. He tells you do not want a MCT cancer..it’s deadly but they don’t do much with dogs diagnosed. He’s a great vet but very much of the mentality that if your dog gets cancer, it’s a death sentence and you can wait or euthanize. No chemo/radiation here. Anyway, I tell him I need this exam to be very thorough and point out the new shoulder tumor. The haunch bumps are gone for now. The tumor on his shoulder had burst open and was leaking. I asked him to please aspirate it so he did and put it on a slide. He is going to look at it more later and call me tomorrow. They did a chest xray to reveal there are no tumors on his lungs or heart. Whew sigh of relief there for me. His breathing could be due to his 103.5 degree fever. They didn’t weigh and I wished they would have. I know Tango is losing weight. They did another CBC and said nothing is showing up really different. WBC is normal, etc. so now they believe that the fever and lack of effect of the antibiotic–he probably has cancer. They gave me 50 capsules of prednisone, famotidine for his stomach, and I have 3 days left of cephalexon to finish out. I am giving him pred 2xs daily for 3 days and then down to once a day (I fear the once-a-day return because bumps grow then). So I have changed his diet and am feeding him cooked meals the past 2 days, have much more research to do, but am waiting. I have not been able to find anything like Tango’s tumors/bumps where there are many small ones and some big..plus the fact that one is leaking and that lymph node is still enlarged to ping pong size—is this bad? I asked the vet if it is cancerous, can they tell me is it stage 1, 2, or 3. He said they don’t do that. UGH! So I feel like my hands are tired and I’m super suspicious that Tango contracted a virus and now has MCT.
Anyway, I want to order pills for him so I am asking you for your advice. Do I get him apocaps? Another med? I feel like i need to do something and order pills to get them here asap to help the pooch. Now that he’s been on 2 pills of pred yesterday, he is eating and acts more like Tango. He is restless at nighttime though. Do I give him Apocaps and pred??? How about kinavet-is that for him? I don’t know. I don’t want this to be a death sentence if it is MCT and I want to help him! I’m uplifted by the stories of those who have had help on apocaps and have been able to get their dog healthier for a couple of more years. I’m nervous with the leaking one and the lymph node. Anyway, any of your thoughts will help! I miss my city vet but am now living in rural town USA where I definately have to be my dog’s advocate!
Big hugs,
Misty
Dear Dr. Ettinger:
My 8 yr old Italian Greyhound was diagnosed with MCT in July 2012, a couple of weeks later we had the 3 tumors removed (one of the tumors was 7 years old, in all cases we were told the tumors were nothing when first having them aspirated). I have him on Palladia (20mg 3 days per week) and chlorambucil now everyday. I’m concerned this is invading the quality of his life and wanted to give you his pathology report to ask your opinion on if I’m doing the right thing. At first I was giving him 10mg palladia Mon, Wed and Fri and Chlorambucil Tues, Thurs, Sat and Sunday. No side effect at all. Now the dosage increased to 20mg palladia Mon, Wed and Friday and the chlorambucial once per day, everyday. He threw up one time and has had very loose, if not water stools. I’m scared to death I’m doing the wrong treatment. Here is his pathology: on his chest Mitotic indext is less than one. Diag: grade 2 (the grading scale seems very subjective to me). The cranial margin is tumor free by approx 0.2 cm. The deep martin is approx 0.2 cm. Ventral and dorsal margins are approx 1.5 cm. On his ear, mitotic index is less then one, they grade this tumor a 1. Excision appears complete with a proximal normal margin of approx 1cm. Finally his let, again the mitotic index is less than 1. This tumor was also graded a 2. excision appears to be complete with margins of approx 0.5 cm medially and laterally. Distal and proximal margins are approx 1.5 cm. I also have my dog on some supplements including k9 critical and curcuVET-SA 50. The supplements are great for him, I have tried him with and without the supplements and am of the opinion the supplements help. My question is this.. the tumors were all successfully removed and the chemo is for preventative care, as I have been told he has a 50% chance of growing another tumor. I love my dog and would bear no expense to ensure his health and happiness. Can you tell me what your opinion of chemo is, at least in my dogs situation? I do not want to take away from his happiness. It should also be noted we did not bring him into the vet for cancer, he was acting just fine ie: food, exercise (3 mile walks), mood, etc. We brought him into the vet for a dental and asked to have all of the 3 tumors re checked because although they did not get bigger, they likewise did not go away. The findings the 2nd time around came back with mast cell cancer. Any suggestions would be greatly appreciated. Thank you so much!!!
Have just started reading the excellent book but had a question in the meantime please. Our labrador has recently had a sizeable Grade 3 MCT removed from his chest cavity. It had a relatviely low MI of 3 but the invasiveness and other factors determined it was a Grade 3. The surgery was a success with clean margins and staging (ultra sound, CT scan, bloods, urinalysis, apsirates of spleen and lymph nodes) were all clear. However because it was a Grade 3 follow up treament is required. The chemo (vinblastine) given before surgery did not really shrink the tumor. Consequently he has been put on Palladia in conjucntion with steriods.
My question really is that there is nothing to measure the success of the Palladia treatment as the tumor was internal and all his staging tests are clear anyway. There is no obvious end in site with the use of the drug and i dont want to keep him on strong meds longer than necessary but equally am consicous that he may well need them given the grade. Appreciate there is no definitive answer but interested to know thoughts with regards to this and how long should remain on Palladia if remains symptom free. If a grade 3 MCT that has shown no signs of Metataszie at the point of removal is removed with clean margins then is the dog potentially cancer free at this point. A bit confused !
Dear Adam
we are all confused. nobody knows. you guess.
🙁
btw don’t forget about all the other aspects of dog cancer treatment
https://www.dogcancerblog.com/blog/an-overview-of-what-else-can-i-do/
Best
D
Adam,
If I am understanding all the info about your dog, grade 3 MCT with no evidence of metastasis at diagnosis, I think chemo post surgery in a great idea. Grade 3 tumors have a 50-90% spread rate, so the goal is to prevent spread. I would suggest about 6 months of therapy. Then if no evidence of spread at that time, discussed stopping therapy with your oncologist.
Good luck! All my best, Dr Sue