The prognostic significance of single hormone receptor positive metastatic breast cancer: An analysis of three randomised phase III trials of aromatase inhibitors

Abstract

We analysed the outcomes of women with metastatic breast cancer (MBC) from three randomised phase III trials of aromatase inhibitors according to oestrogen receptor (ER) and progesterone receptor (PgR) status. Both receptors were analysed in 1010 of the 1870 women (54%), including 31 that were ER-/PgR-, which were excluded. Of the remaining 979, 726 (74%) were ER+/PgR+ but 253 were single hormone receptor positive (213 ER+/PgR-, 40 ER-/PgR+). Although there were no differences in clinical benefit or time to progression, the median overall survival of women with ER+/PgR+ tumours was significantly longer than those with single HR positive tumours (800 versus 600 days, p = 0·01). In women with ER+ tumours, the median overall survival of those with tumours that were also PgR+ was significantly longer than those that were PgR- (800 versus 625 days, p = 0·02). The PgR status is an important prognostic factor for survival in MBC.