Clinical characteristics of mammary carcinoma in male cats.

There is little information regarding mammary tumors in male cats. The purpose of this study was to characterize the clinical characteristics of mammary carcinoma in male cats, compare this malignancy to the disease in female cats, and identify prognostic factors. Thirty-nine male cats with mammary carcinoma were identified. One pathologist reviewed the biopsies from all cats, and complete follow-up information regarding outcome was available for 27 cats. Information collected included signalment, age at neutering, history of progestin therapy, age at tumor diagnosis, size of tumor, type of surgery (lumpectomy, simple mastectomy, or radical mastectomy), results of clinical staging, adjunctive therapies, time to local recurrence, survival, and cause of death. The mean age at tumor diagnosis (12.8 years) was slightly older than that reported in female cats. The incidence of local tumor recurrence in 9 of 20 (45%) cats was similar to that reported in females. A history of progestin therapy was present in 8 of 22 (36%) cats for which this information was known. The median time to local recurrence was 310 days (range 127-1,363 days), and overall median survival was 344 days (range 14-2,135 days). Tumor size and lymphatic invasion were identified as negative prognostic factors. This study indicates that mammary carcinoma in the male cat has many similarities to the disease in females, with an aggressive clinical course in most cats.