Boland MR, et al. - Researchers performed a meta-analysis to determine the impact of progesterone receptor (PgR) negativity on outcomes in estrogen receptor (ER)-positive (ER+) breast cancer. Systematical searches of PubMed, Embase, and the Cochrane Library yielded 8 eligible studies representing 13,667 patients for inclusion; 11,838 patients comprised the ER+PgR+ group and 1,829 patients comprised the ER+PgR– group. The investigators noted an association of PgR negativity with significant reductions in disease-free and overall survival in ER+ breast cancer. They recommended tailoring treatment and surveillance strategies in these patients accordingly.