Ectopic production of prostate specific antigen by a breast tumor metastatic to the ovary.

We have recently reported that about 30% of breast tumors produce prostate specific antigen (PSA). We examined here, 99 primary ovarian cancer tumors and found relatively low levels of PSA in only three tumors. One patient with metastatic ovarian cancer from a primary breast tumor, produced relatively high levels of PSA and responded well to antiestrogen treatment although she was steroid receptor-negative. Another patient with metastatic ovarian cancer from a primary breast tumor did not produce PSA and did not respond to treatment although she was steroid hormone receptor-positive. This data describe for the first time, ectopic PSA production by a breast tumor at the ovarian metastatic site and further support the view that PSA is a favourable prognostic indicator in breast cancer.