Adjuvant chemo-endocrine therapy for androgen-dependent mammary tumor in mice

About 500 male DS mice grafted with androgen-dependent Shionogi carcinoma 115 (SC115) were used. When the tumor diameter reached about 20 mm (approximately 25 days after transplantation), excision of the tumor and/or castration were carried out. The injection of cyclophosphamide (80 mg/kg body weight X 3 at 7-day intervals) was started from the day after excision. In mice with excised tumor, adjuvant chemo-endocrine therapy was the most effective treatment examined; cumulative 120-day mortalities after transplantation of tumors in non-treated, adjuvant endocrine therapy, adjuvant chemotherapy and adjuvant chemo-endocrine therapy groups were 91%, 29%, 21% and 0%, respectively. Castration induced development of clusters of androgen-independent cancer cells in androgen-dependent SC115 tumor. In mice without tumor excision, the chemo-endocrine therapy was again the most effective treatment, though 86% of mice died by the 120th day after tumor transplantation. These findings suggest the usefulness of adjuvant chemo-endocrine therapy for achieving complete remission in hormone-dependent tumors.