Trends in U.S. breast cancer mortality by estrogen receptor status.

Evaluating breast cancer mortality by estrogen receptor (ER) status can help inform strategies to reduce the U.S. breast cancer burden. We used SEER 17 registries to calculate age-standardized breast cancer incidence-based mortality (IBM) rates per 100,000 person-years from 2009-2022 by ER status (positive/negative) and compared with incidence and 5-year relative survival. We estimated trends using average annual percent change (AAPC). For ER-positive breast cancers, IBM rates marginally increased from 2009 (16.6) to 2014 (17.2) and then decreased by 2022 (15.2) (AAPC:2009-2022=-0.65%,95%CI=-1.35%,0.05%;AAPC:2014-2022=-1.53%,95%CI=-1.88%,-1.19%). Incidence rates decreased then increased again, with small increases in survival. For ER-negative breast cancers, IBM rates decreased significantly (2009=9.6,2022=6.4;AAPC=-3.33%,95%CI=-4.17%,-2.48%) in parallel with declining incidence rates and significant survival improvements. In 2022, ER-positive breast cancers accounted for 5-times more cases and 2-times more deaths than ER-negative; despite effective therapies, ER-positive mortality did not have substantial declines, indicating public health opportunities to reduce the population burden of breast cancer mortality.