Get Dr. Dressler's Dog Cancer Diet FREE Many dog lovers really struggle with decisions in dog cancer care.
One reason is that there are so many uncertainties. Ethical questions by nature do not have black and white answers.  Median survival times are basically just a type of average, and may not hold for a given dog. Side effects are all just probabilities, and you never know if your dog’s number will come up in the roulette wheel. Data on unconventional therapies is lacking.
So it can be incredibly frustrating when you and your canine companion are in this “gray zone”.
One of the reasons you are here is to try to lessen uncertainties by getting more information. So let’s look at some data that can help you guide the treatments for your dog, in particular in those borderline cases where we are not sure how the cancer will behave.
The most common instance of this is the grade 2 mast cell tumor. As many know, the grade is a measure of how aggressive a cancer is. When we say a cancer is a “high grade malignancy”, this means it is hard to cure. A “low grade” growth is easier to cure as a generality (but not always), usually by surgical removal.
In mast cell tumors, the grade is broken down into three levels, with grade 1 being the lowest and grade 3 being the highest and most aggressive. Aggressive cancers are those that do things like regrow after surgery, spread to surrounding areas (local invasion), or spread to distant sites to places like the spleen, liver, bone marrow, or other remote areas (metastasis).
Grade 2 mast cell tumors are intermediate, by definition, and unpredictable. Or at least they have been in the past. In other words, grade 2 mast cell tumors can sometimes behave aggressively (like grade 3′s) or other times behave like more benign growths (grade 1′s).
If your dog’s pathology report (after the growth is biopsied) shows a grade 2 mast cell tumor, what is the action plan? A second wide excision surgery? Chemotherapy? We are in limbo…unless we consider another bit of information:
The mitotic index!
This is a measure of how many cells are dividing within the tumor. The more cells that are dividing, the more aggressive a given tumor is generally. Mitosis in this case is simply the process of cell division. More cell division, faster growth, higher mitotic index.
The pathologist simply looks at a slide with a very thin slice of your dog’s tumor tissue on it, which has been stained so it is colored. They can tell which cells are dividing (in mitosis). They simply count the numbers of these cells and viola, the mitotic index is calculated.
What is the data?
Lower mitotic index is better. This means that fewer dividing cells means a less aggressive cancer. The magical numbers for a grade 2 mast cell tumor is a mitotic index of 5 or less. These dogs, with conventional care alone, have a median survival time of 70 months.
However, dogs with a mitotic index of greater than 5 had a dramatically shorter median life expectancy of only 5 months. This is quite a dramatic difference.
So in those cases where we have a grade 2 mast cell tumor with a mitotic index of under 5, a wide excision should be done at a minimum, but the other steps (chemo, radiation) should be carefully considered before jumping in. Do they make sense?
in cases where we are looking at grade 2 mast cell tumors with a mitotic index of greater than 5, these cancers should be considered very , very dangerous and aggressive. For those who have a dog much less than her average life expectancy, be more aggressive with the treatments. Consider chemo and radiation with your oncologist. For those whose dog is close or beyond his average life expectancy, it is time for ethical considerations and focus on life quality enhancement.
Diet, supplements, life quality enrichment, and the other complementary aspects of care should always be on your radar, regardless of grade or mitotic index.
For those who would like more on treatment plan analysis, check out The Dog Cancer Survival Guide.
Best,
Dr D
About the Author
Dr. Demian Dressler, DVM is known as the "dog cancer vet" and is author of Dog Cancer Survival Guide: Beyond Surgery, Chemotherapy & Radiation. Visit his blog and sign up free to get the latest information about canine cancer. Go to http://DogCancerBlog.com.
{ 6 comments… read them below or add one }
Hi Dr. Dressler,
I just came across this post and was wondering if you could help me with a question? My dog had a grade II MCT on her skin that was removed in August 2008 and we found in August 2009 that it has spread to a lymph node on her chest. That was removed with clean margins and she underwent chemo (vinblastine and pred) and is doing well.
I came across this post and went and checked her records (which I got from the clinic thanks to your ebook) and saw that it said “one or two” cells were in mitosis per 400x field (on the pathology report from the lymph node.) So, what would be the mitotic index for that? Is it one or two? Or higher?
My dog’s oncologist did not mention M.I. to me, and I did not think to ask about it at the time.
Thank you!
Allie
Your book and blog don’t mention hemangiopericytoma or fibrosarcoma. Any input on those?
I’m also wondering if your vitamin D information is up to date.
Vitamin D levels can definitely be improved in humans, and the current recommendations for the majority of people is 10,000 IU for 6 months, then test levels. This is considered the #1 bang for your buck regarding cancer.
So it would be surprising to me that dogs really can’t benefit from supplements, and I wonder if they truly get toxicity at low levels, or if that is that old information. A year ago a lot of doctors were saying that people could get toxicity from 1000 or 2000mg of D. And that has been proven as false.
Dear Allie
The mitotic index refers to the biopsy of the cancer itself, not a lymph node. Which are you referring to here?
Dr D
Dr. Dressler, my almost 6 year old American Bulldog just had a mast cell tumor removed, it was a grade II with mitotic index of 9. She is overall healthy happy and now that the stitches are removed seems to be back to normal. Met with oncologist who recommended Vinblastine and Pred for 8 weeks. My question, the tumor removed had clean margins, they got it all according to pathologist, is chemo worth the side effects given this bad tumor was removed cleanly? This dog gets really nervous at the vet, stresses her out badly, very badly. I hate to take her to the oncologist for 8 weeks unless I knew it was worthwhile for her life. Any comments or recomendations for me on a cleanly excised grade II tumor with mitotic index of 9? Is it possible that it is cured now???
Dear Matt,
Although it is possible you have a cure, the mitotic index suggests that it may be a more aggressive (and potentially life threatening) cancer. The issue of margins does not really apply to cancers that tend to spread to distant sites:
http://www.dogcancerblog.com/dog-cancer-what-is-micrometastasis-and-why-do-we-care/
I hope this helps,
Best,
Dr D
My 11 1/2 years old golden retriever, Honey, passed away Monday August 23. Her path report noted liver cancer – primary hepatic/biliary carcinoma but could also be metastastic – so no definitive report. Her last ultrasound, taken on the 18th, showed that 2 lymph nodes were greatly enlarged along with her liver. She had had surgery 2 years ago to remove a thyroid tumor in her neck. It had not metastisized and she got along great after surgery. I was told that, if the carcinoma in her liver was thyroid, Kinavet could help. I decided to try the drug. At this point, there was no telltale signs of the cancer. I gave her 200 mg on Wed night; I gave her another 200 mg Thursday night. She was feeling bad and had diarrhea – a small amount; also, her nose started running- water would drip freely from her nose; Friday I came home from work to check on her and found that she had vomited bile; She wouldn’t eat Friday but drank water. I decided to stop the Kinavet and called the vet, who agreed and prescribed a nausea tablet. Sat am she had diarrhea; by midday she had drank some water, ginger ale and ate a can of chicken noodle soup by 10pm; however she was totally weak. Sun she wouldn’t eat or drink – water was dripping from her nose and her eyes were running, like she was crying. Sun afternoon she vomited very mucousy bile 3 times – I took her to the emergency room and was told she was dehydrated. Mon am the vet called to tell me she had walked around a bit however, her heart chambers were not pumping in sync – the chambers were pumping randomly although there was oxygen in the blood. She was going to monitor Honey another day and do another blood panel. Less than 20 min after the 1st call, she called to tell me her heart had stopped. Could the dehydration with the Kinavet in her system caused her heart to shut down? How long would the Kinavet remain in her system – (she weighed 61 lbs)? I was supposed to give her 200 mg every 24 hours and I gave her the drug on Wed and Thurs. I had breast cancer – mastectomy and chemotherapy. I had a heart check to determine the strength and health of my heart before chemo was started. I realize that my drug was different and of course I’m a human. Could the 400 mg of Kinavet strained/harmed her heart? The vet also told me Mon that she showed signs of jaundice in the whites of her eyes. The cancer was found in her liver -could the Kinavet have stressed her liver enough to cause it to shut down? I got Honey when she was 7 weeks and she has been my child, best friend and companion. I am trying to deal with the reality that she’s gone (it’s like a bad bad dream ). I made the decision to try the Kinavet as I wanted to keep her with me as long as possible. Please help me find some answers. The vet said that she thought Honey had issues we weren’t aware of. It happened so fast. Wed day she ate well, ate several milk bones and went for a walk with me Wed night albeit she walked slow and wasn’t her usual perky self. Mon she was gone. If her cancer was advanced, would she have gone so fast in the course of 4 days? Please help me.