Testolactone Acetate blocks the production of the hormone estrogen. Certain types of breast cancer require estrogen to grow.Testolactone is used to treat some types of breast cancer.Testolactone may also be used for purposes other than those listed in this medication guide. Testolactone Acetate is a synthetic anti-neoplastic agent that is structurally distinct from the androgen steroid nucleus in possessing a …