Concordance and discordance of estrogen and progesterone receptor content in sequential biopsies of patients with advanced breast cancer: relation to survival.

In 75 patients with advanced breast cancer, sequential biopsies were analyzed for estrogen receptor (ER). In 50 of these patients progesterone receptor (PgR) was also measured. All pairs of biopsies met the following criteria: (i) interval between the two biopsies: at least 6 weeks; (ii) biopsies performed at least 6 weeks after stopping endocrine therapy; and (iii) concordant histology. Discordance in ER was found in 14 of 75 patients (18.7%); PgR was discordant in 14 of 50 patients (28.0%). No significant differences were found between concordant and discordant groups of patients in age at first diagnosis, menopausal state, diameter of the primary tumor, time interval between the two biopsies and intervening therapy. The initial ER level in patients whose ER changed from positive to negative was significantly lower than in patients whose ER remained positive. PgR levels exhibited a rise only when ER rose at the same time. Sequential assays have increased the prognostic significance of ER and as a consequence the estimated survival time for patients whose tumors were ER-negative in both biopsies was significantly shorter than for patients whose tumors were ER-negative in only one of the two biopsies. We found no prognostic significance for PgR in either single measurements or repeated biopsies.