ESR1 and breast cancer: When considering BC per combined estrogen and progesterone status, we found the strongest associations between residential road traffic noise (for each 10 dB increase in 24-year mean noise levels preceding diagnosis) and ER+/PR+ (HR; 95% CI, 1.22; 1.02–1.42, N = 384) and ER+/PR- (HR; 95% CI, 1.33; 0.97–1.82, N = 110), and none with ER-/PR+ (N = 9) or ER-/PR- (N = 108) BCs (Table 4).