I get a lot of inquiries that relate to whether a cancer is gone after it is removed, or what will be the outcome.
Sometimes these are tough to answer, and the reason is micrometastasis.
Micrometastsis occurs when a cancer spreads from a site, but the spread is not detectable by the usual means available. Only a few cells take off, traveling perhaps in the circulation to set up shop elsewhere in the dog’s body. So few cells spread, that they are undetectable.
So you have someone like me take the tumor out, for example, and the borders are examined by a pathologist to see if the margins are “clean” (no cancer cells at the edge, they are all located near the center of the removed piece, suggesting complete removal). Your path report says “complete excision” (complete removal).
Say though, that you are faced with the diagnosis of a malignant melanoma, a Grade 3 mast cell tumor, an osteosarcoma, an advanced squamous cell carcinoma, a large hemangiosarcoma, or some other kind of canine cancer with a known tendency to spread.
Suppose your vet or oncologist was very thorough and did all that could be done to see whether there was evidence of spread, and all the tests were negative. But your vet or oncologist is still pessimistic. Why?
Micrometastasis. The cancer did spread, but only a few cells. These can sneak up on us later, turning up as cancers that were not there at the time we checked, but were there later.
This is why we are sometimes talking about steps beyond surgery when there is no evidence the cancer has spread. We want to make sure we are addressing the known tendency of these cancers to take off, even when the tests looking for spread are negative.
Best to all,
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.