Abstract A102: Nationwide Racial, Ethnic, Geographic and Stage-Specific Trends in Breast Cancer Incidence among Older US Women, 2001-2019

Abstract Purpose: Breast Cancer (BC) incidence is increasing among younger women with significant variation by race, ethnicity, and geography. Yet, few studies have described trends and possible social disparities among the oldest women (65+), typically grouping older women into a single age category, despite age-related variation in screening guidelines (e.g., no longer recommending routine screening beyond age 74 or limited life expectancy). We assessed trends in US BC incidence rates among 3 separate age groups of older women (65-74y, 75-84y, 85+) by stage at diagnosis, race, ethnicity, and geography. Methods: To cover all 50 US states, we used the US Cancer Statistics (USCS) public use database, 2022 submission of NCPR and SEER incidence data to obtain annual BC incidence rates from 2001-2019, age adjusted to the 2000 US standard population. We used Joinpoint regression to obtain the average annual percent changes (AAPCs) in BC incidence rates for each age group over the time period stratified by disease stage at diagnosis, race/ethnicity, metropolitan status, and region. Results: From 2001-2019, overall BC incidence rates per 100,000 were 530.4, 515.3, and 376.8 for ages 65-74, 75-84, and 85+, respectively. During this period, incidence increased by 0.4% (95% CI: 0.2 to 0.6) per year in women aged 65-74, remained stable in women aged 75-84 years, and decreased by 1.1% (95% CI: -1.4 to -0.8) per year in women aged 85+ years. In all age groups, there was a decline in regional stage (AAPCs range -0.8 to -0.9) and an increase in distant stage (AAPCs range: 1.1- 1.6). However, in situ and localized stage trends varied by age group (e.g., both increased in 65- 74, but decreased for 85+). For all stages combined, in the 65-74 year-old age group, non- Hispanic Black, American Indian/Alaska Native, Asian/Pacific Islander, and Hispanic women had 7-11 times the rate of average annual percent increase compared to non-Hispanic White women (AAPCs: 1.6, 1.8, 2.2, and 1.4 vs. 0.2, respectively). Rates increased for non-Hispanic Black and Asian/Pacific Islander women (AAPCs: 1.0 and 0.9, respectively) in the 75-84 year old age group and decreased for non-Hispanic White and Hispanic women aged 85+ (AAPCs: -1.0 and -1.3, respectively). Age-specific trends did not vary by metropolitan status, though BC incidence rates were lower in non-metropolitan vs. metropolitan areas across all age groups (non- metropolitan vs. metropolitan rate ratio range: 0.90-0.95). BC incidence in 65-74 year-old women increased from 2001-2019 in the Northeast, Midwest, and South, increased in the Northeast (AAPC: 0.2) and decreased in the West for ages 75-84, (AAPC: -0.6), and decreased in all 4 regions of the US (AAPC range: -0.7 to -1.5) in the 85+ year-old age group. Conclusions: As previously reported for younger women, these findings support racial, geographic, and stage- specific BC variation in trends are also observed for older women. Further research should examine the contribution of screening practices to these trends and their impact on BC mortality disparities among older women. Citation Format: Erica Lee Argov, Anita Karr, Michelle Lui, Parisa Tehranifar, Rebecca Kehm. Nationwide Racial, Ethnic, Geographic and Stage-Specific Trends in Breast Cancer Incidence among Older US Women, 2001-2019 abstract. In: Proceedings of the 17th AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2024 Sep 21-24; Los Angeles, CA. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2024;33(9 Suppl):Abstract nr A102.