PROGESTERONE BINDING CYST PROTEIN IN HORMONE-RECEPTOR POSITIVE BREAST-CANCER - A PREDICTIVE FACTOR FOR EFFECT OF ADJUVANT TAMOXIFEN TREATMENT

Progesterone binding cyst protein (PBCP) was measured in beast cancer cytosols from 128 pre- and postmenopausal women with operable node pos itive (pN+) breast cancer Stage II. All patients were included in a na tional multicenter study on the effect of adjuvant tamoxifen treatment in hormone sensitive breast cancer, i.e. estrogen receptor content of at least 10 pmol/g cytosol protein. Patients were randomised to recei ve adjuvant tamoxifen 20 mg once daily for two years or no endocrine t reatment. At a median follow-up of 60 months, we found PBCP content in the primary tumor to be an important factor with regard to the effect of adjuvant tamoxifen treatment. The benefit of adjuvant tamoxifen tr eatment on relapse-free survival and overall survival was confined to the subpopulation of patients with PBCP negative tumors. PBCP should b e further evaluated as a predictive factor for the effect of tamoxifen treatment.