Biogenesis of steroid hormones by human mammary gland in vivo and in vitro

The ability of human breast tumours to synthesise steroid hormones was studied by perfusion of the human breast in situ and incubation of the neoplasms in vitro. The results obtained indicate that these tumors are capable of converting pregnenolone and dehydroepiandrosterone to progesterone and androstenedione respectively. Other enzymes normally associated with androgen and oestrogen synthesis were absent in these neoplasms. The significance of these findings is discussed.