Progesterone receptor activity and relapse-free survival in patients with primary breast cancer: the role of adjuvant chemotherapy.

The prognostic significance of progesterone receptor activity (PgR) with regard to the estimated relapse-free survival (RFS) was studied in 350 one-center patients with primary breast cancer. All receptor assays were performed in one laboratory; PgR levels greater than 10 fmol/mg protein were considered positive. Univariate as well as multivariate statistical analyses were used to examine the prognostic significance of several variables. Eighty-nine of the 350 patients received adjuvant CMF chemotherapy (cyclophosphamide, methotrexate, and 5-fluorouracil). The median observation period was 69 months (range 12-125 months). In the group of 261 patients who did not receive adjuvant CMF, the PgR-status lacked prognostic significance; only the lymph node status significantly affected the RFS (p less than 0.00001). In contrast, in the CMF-treated group of patients, the PgR-status was the most powerful predictor of recurrence (p less than 0.001). Premenopausal CMF-treated patients with PgR+ tumors had a significantly longer RFS than those with PgR- tumors (p less than 0.02). The present data urge the need for a reappraisal of the prognostic significance of PgR and of the mechanism of action of adjuvant chemotherapy in primary breast cancer.