Tissue immunoreactive prolactin hormone in breast cancer

The prolactin contents of the cytosol extracts of 159 human mammary carcinomas was measured by specific radioimmunoassay. Of these extracts 157 contained measurable prolactin (detection limit, 7.8 ng/g tumor). The levels measured were in most cases greater than would be expected to be due to only serum contamination. The levels of prolactin did not correlate with either estrogen or progesterone receptor content of the tumors, or menopausal status of the patient.