Heterogeneity in hormone-receptor status and survival outcomes among women with synchronous and metachronous bilateral breast cancers.

To examine whether discordance in the hormone-receptor status predicts clinical outcomes in patients with bilateral synchronous (SBC) or metachronous breast cancer (MBC), we analyzed data from the Surveillance, Epidemiology, and End Results program (1998-2011) using Cox models. After excluding 10,231 patients with missing data on hormone receptors in at least one tumor, 4403 SBC and 7159 MBC were included in the study. Among SBC cases, patients with estrogen receptor (ER)-discordant tumors had higher mortality risk (multivariable-adjusted hazard ratio [HR] = 1.96, 95% confidence interval [CI] 1.60-2.40) than patients with ER concordant-positive tumors, whereas patients with ER concordant-negative tumors had the highest risk (HR = 2.49, 95% CI 2.03-3.07). Among MBC cases, patients with a positive-to-negative change in ER status (HR = 1.32, 95% CI: 1.08-1.62) or ER concordant-negative tumors (HR = 1.48, 95% CI: 1.19-1.85) had worse survival than patients with ER concordant-positive tumors. In conclusion, discordance in the hormone-receptor status was an independent predictor of survival outcomes.