Carcinoma mammae occurring in a male mouse under continued treatment with oestrin.

Several studies have proven the connection between ovarian activity, or treatment with estrogens, and breast cancer in laboratory animals. This article presents the results of an experiment conducted on 130 male mice of no particular strain, of which 20 had been castrated. The mice were treated with a solution of estrin in benzene for prolonged periods. Only 1 of the mice, a castrated male, developed breast cancer 175 days after the beginning of treatment. The tumor was removed, and an autograft was made in the right groin; 58 days after the autograft the mouse was killed. The grafted tumor had penetrated the abdominal wall and numerous metastases were present. On the other hand, grafts from the original tumor given to 10 young mice did not give rise to any additional tumors.