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,