Trends in breast cancer incidence by estrogen receptor status in the United States, 2004–2020.

Divergent trends of breast cancer incidence by subtype have been reported in the United States and elsewhere; however, it remains unknown whether this trend has continued until the era of the COVID‐19 pandemic. Using high‐quality population‐based cancer registry data, representing 83% of the US population, this study examined breast cancer incidence rates by estrogen receptor (ER) status in women aged 20–84 years from 2004 to 2020. The incidence rate of ER‐positive cancer increased by 1.75% per year from 2004 to 2009 (95% confidence interval [CI] = 1.26%–3.15%) and has slowed to a 0.87% annual increase (95% CI = 0.41%–1.03%) from 2009 to 2019, followed by a 10.2% reduction from 2019 to 2020. Trends were generally similar across race and ethnicity, although young women (20–49 years), Asian or Pacific Islander, and Hispanic women experienced steady increases until 2019. The incidence rate of ER‐negative cancer decreased by 3.13% annually (95% CI = −4.2% to −2.55%) from 2004 to 2012, and the decrease stabilized from 2012 to 2019 (annual percent change: 0.55%; 95% CI = −1.30% to 0.92%), followed by a 6.0% reduction from 2019 to 2020, with trends generally consistent by age and across racial and ethnic groups. The stabilization of the steep decline in ER‐negative cancer suggests a departure from the encouraging trajectories projected in earlier studies. Coupled with the deceleration in the rise of ER‐positive cancer, the latest trend signals a potential stabilization in the previous rise of the proportional burden of ER‐positive cancer. Understanding the impact of the pandemic on each subtype of breast cancer individually may provide a more comprehensive insight into its long‐term sequelae on survival and mortality. [ABSTRACT FROM AUTHOR]