Prognostic factors in canine mammary cancer.

From a follow-up study of dogs surgically treated for mammary cancer, ten characteristics were analyzed statistically with special reference to their association with prognosis (expressed as survival for 2 years). The interrelations among five of the characteristics were also tested. The histologic type (descending range in malignancy: sarcomas greater than simple carcinomas greater than complex carcinomas), mode of growth (highly infiltrating greater than moderately infiltrating greater than expansive), clinical stage of complex carcinomas (large tumors and/or tumors involving the skin or underlying tissue greater than small, well-defined tumors), and size (greater than 15 cm greater than 11-15 cm greater than 5-10 cm greater than 0-5 cm) were of definite prognostic importance. The histologic grade was of possible prognostic importance. Localization, type of surgical therapy (mastectomy, block-dissection), growth in lymph vessels, involvement of regional lymph nodes, and duration of symptoms before treatment were not important to prognosis. A comparison between the factors associated with the prognosis of canine and human mammary cancer showed many similarities. However, the involvement of regional lymph nodes, important in women, was not so in bitches.