Testosterone metabolism in benign and malignant breast lesions.

Tissues from a variety of breast lesions were incubated with 14C-testosterone (17beta-hydroxy-4-androsten-3-one). Conversion to 14C-5alpha-dihydrotestosterone (17beta-hydroxy-5alpha-androstan-3-one) and 14C-androstenedione (4-androsten-3,17-dione) was measured. Normal breast tissue showed formation of 14C-androstenedione but no formation of 14C-5alpha-dihydrotestosterone. Fibroadenomas showed a high degree of testosterone metabolism forming both 14C-androstenedione and 14C-5alpha-dihydrotestosterone. The adenocarcinomas of the breast, contrary to a previous report in the literature, showed no conversion to 14C-5alpha-dihydrotestosterone. The data suggest that formation of 5alpha-dihydrotestosterone is a predominant metabolic pathway in fibroadenoma.