Breast Cancer Incidence Trends in Older US Women by Race, Ethnicity, Geography, and Stage.

Importance: Breast cancer (BC) incidence trends are known to vary by race, ethnicity, and geography among younger women. Less is known about trends among older women (aged ≥65 years), who are typically aggregated, despite different screening guidelines for those older than 74 years. Objective: To disaggregate US BC incidence trends among older women (ages 65-74, 75-84, and ≥85 years) according to stage at diagnosis, race and ethnicity, hormone receptor subtype, and geography. Design, Setting, and Participants: This population-based cross-sectional study included women aged 65 years and older who were diagnosed with BC from January 2001 to December 2019. Data came from the US Cancer Statistics public use database, with information on women in all 50 US states. Data were analyzed from March to June 2024. Exposure: Age (65-74 years, 75-84 years, and ≥85 years). Main Outcomes and Measures: Age-adjusted BC incidence rates were obtained, and average annual percent changes (AAPCs) from 2001 to 2019 were estimated using joinpoint regression for each age group, stratified by stage at diagnosis, race and ethnicity, and geography. Results: From 2001 to 2019, 2 278 611 women (1 249 750 [54.9%] aged 65-74 years; 119 287 [5.2%] Hispanic [all races], 205 738 [9.0%] non-Hispanic Black, and 1 826 084 [80.1%] non-Hispanic White) were diagnosed with BC. Age-adjusted BC incidence rates were 530.4 (95% CI, 529.5 to 531.3) per 100 000 persons, 515.3 (95% CI, 514.2 to 516.5) per 100 000 persons, and 376.8 (95% CI, 375.3 to 378.2) per 100 000 persons for ages 65 to 74 years, 75 to 84 years, and 85 years and older, respectively. Annually, incidence rates increased in women aged 65 to 74 years (AAPC, 0.4%, 95% CI, 0.2% to 0.6%), remained stable in women aged 75 to 84 years, and decreased in women aged 85 years or older (AAPC, -1.1%, 95% CI, -1.4% to -0.8%). In women aged 65 to 74 years, the AAPC was 7 to 11 times higher in Hispanic, non-Hispanic American Indian or Alaska Native, non-Hispanic Asian or Pacific Islander, and non-Hispanic Black women compared with non-Hispanic White women. Across all age groups, regional stage diagnoses decreased (ages ≥65 years: AAPC, -0.8%, 95% CI, -1.1% to -0.5%), while distant stage diagnoses increased (ages ≥65 years: AAPC, 1.3%, 95% CI, 1.2% to 1.6%). Trends for in situ and localized diagnoses varied by age. Across all age groups, non-Hispanic Black women had the highest proportion of hormone receptor and ERBB2-negative cancers. Conclusions and Relevance: In this population-based cross-sectional analysis of BC incidence trends among older US women, racial and ethnic as well as stage-specific patterns differed across age groups, highlighting the importance of disaggregating BC incidence rates into age groups better aligned with screening guidelines. Future research is needed to directly examine the contribution of screening patterns to these trends and their impact on BC mortality.