Dog cancer: What is Micrometastasis and Why Do We Care?
ByI 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 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.
5 Comments
October 29th, 2008 at 11:15 am
You wrote:
This is why we are sometimes talking about steps beyond surgery when there is no evidence the cancer has spread.
Having a 12yo Lab with a huge hemangiosarcoma 3 mos ago, what tests do you recommend, and at what inntervals? Currently, we are doing a chest xray, abdominal utz, and a detailed blood check.
October 29th, 2008 at 11:36 am
I assume it was removed??
I cannot give recommendations for specific animals on this blog. However, generally speaking, for dogs with hemangiosarcomas that were removed, and are judged stable by the vet working on the case, one protocol could be ultrasounds and chest films every 3-4 months, along with CBC’s,full chemistry panels and urinalysis at the same interval. Of course this is dictated on the individual patient’s needs. Good luck!!
D
October 29th, 2008 at 11:37 am
I should also mention this should include complete physical examinations and aspirates or biopsies of any enlarged lymph nodes or further masses found.
D
October 30th, 2008 at 3:03 am
Cathy, my Mali was dx splenic HSA on 12/20/2004. Her spleen ruptured and required an emergency splenectomy. We did 5 rounds of Adriamycin chemo and still do chemo maintenance and antiangiogenesis. She has great quality.
While doing chemo, we did chest x-rays, abdominal ultrasounds and CBC’s every month to monitor how she was handling her chemo and to see what may or may not be lurking. After her chemo, we went every 2 to 3 months. After year 2 post dx, we went every 3 to 4 months. We are nearing year 4 post dx and now go every 6 months for scans, but still do the CBC’s and a physical exam every 3 months, as she is on so many meds and supplements. Throughout all this time, we gone in for needle aspirates and/or removal of suspicious lumps and bumps.
Best to you and your Lab from me and my Lab.
November 2nd, 2008 at 8:55 am
My Tigger had mass removed last Aug 07 from liver dx. hepatocelluar carcinoma. ( CLEAN MARGINS.) Had rechecks every 8 weeks and in May 08 mass came back in liver right in the middle. Surgery was not advised so far TIGGER HAS HAD TWO CHEMOEMBOLIZATIONS TO SHRINK THIS TUMOR.