Q.: What does tumor recurrence mean? My dog had a large sarcoma removed from his side. My veterinarian is concerned about the tumor growing back. How can the tumor grow back if it is no longer visible. Why is it a poor prognosis for my dog if the tumor regrows?
A.: The regrowth of a tumor in its original location can occur, and is commonly seen with tumors called sarcomas, which is the type of tumor removed from your dog. The diagnosis is made when the tumor is removed and the tissues are examined by a pathologist.
Sarcomas are tumors that grow very aggressively, and have microscopic tendrils of tumor cells that dive into the deeper tissues and are impossible to remove surgically. Although the primary tumor is no longer visible, there is still residual microscopic disease present at the location of the original tumor. These microscopic tumor cells start to multiply and divide. They are able to easily obtain nutrients and oxygen from the microenvironment, since the large bulky tumor has been removed and the microscopic cells no longer have to compete with the large tumor for nutrients.
As the cells multiply and divide, they form a visible mass at the location of the original incision line. This is what we call tumor regrowth. Depending upon a number of factors, the tumor can regrow in as little as 30 days, or may take as long as a year to regrow. The concern with regrowth is that the tumor becomes even more aggressive when it regrows, and the chance for distant metastasis increases each time the tumor regrows.
In general, the treatment we use to destroy microscopic tumor cells before they regrow is radiation therapy. This type of treatment is very effective at destroying tumor cells and most dogs with sarcomas are cured after receiving radiation treatment. Therefore, by preventing tumor regrowth patients have a very favorable long-term prognosis.
Stephanie Correa, DVM
Board Certified in Oncology
Animal Cancer Care Clinic
www.AnimalCancerCareClinic.com
Read more articles by Dr. Correa | Ask her a question
Source: http://blogs.palmbeachpost.com/pawshere/2013/08/08/radiation-can-help-prevent-tumor-regrowth/