Abstract PS4-09-21: Disparities in Breast Cancer Mortality Among Individuals with Mental and Behavioral Disorders: A 25-year population-Based Analysis

Abstract Background: Breast cancer (BC) mortality has declined in the general U.S. population over recent decades. However, individuals with mental and behavioral disorders remain an understudied and potentially high-risk subgroup. This study aims to assess national trends in BC mortality among women with mental and behavioral disorders, stratified by race and ethnicity. Method: We studied a cumulative population of 9.17 billion by using the CDC Multiple Cause of Death database (ICD, 10th revision) between 1999 and 2023. We identified all women who died of BC, code C50, as underlying cause of death (UCD), regardless of mental and behavioral disorders (MBD). Then we identified the same UCD among women with MBD, code F01-F99, as multiple cause of death. Age-adjusted mortality rates (AAMR) per million persons (PMP) were calculated, standardized to 2000 US census, and stratified by ethnicity and race Hispanic (H), non-Hispanic (NH), Black (B), White (W), Asian or Pacific Islander (A/PI), and American Indian or Alaska Native (AI/AN). Annual percentage changes were calculated to assess the mortality trends. Result: In the general population (GP), a total of 2,059,043 deaths from BC were identified, with an overall AAMR of 188.3 PMP (B: 296.3, W: 219.9, A/PI: 117.1, AI/AN: 123.5, H: 143.9, NH: 229.3). AAMR declined from 1999 to 2023 by 28% among B from 349.8 to 252.2 PMP, 30% among W from 259.7 to 183 PMP, 12% among A/PI from 126.2 to 111.7 PMP, 34% among AI/AN from 154.9 to 102.7 PMP, 18% among H from 164.3 to 135.5 PMP, and 27% among NH from 272.1 to 194.4 PMP. In the population with MBD, a total of 175,198 BC deaths were identified, with an overall AAMR of 8.7 PMP (B:12.5, W: 11.2, A/PI: 3.4, H: 4.5, NH: 11.86). AAMR increased from 1999 to 2023 by 222% among B from 4.9 to 15.8 PMP, 230% among W from 4.4 to 14.5 PMP, and 243% among NH from 4.4 to 15.1 PMP. Excluding years with unreliable data, the AAMR doubled among H, rising from 2.5 to 5.0 PMP (a 100% increase) from 2002 to 2023, and remained relatively stable among A/PI, declining slightly by 12.1% from 3.3 to 2.9 PMP between 2010 and 2023. No reliable data were identified among the AI/AN. Conclusion: This is one of the largest population-based studies analyzing BC mortality in women with MBD. While breast cancer mortality declined across all racial and ethnic groups in the GP over the past two and a half decades, substantial increases were observed among those with MBD. In sharp contrast to declining rates in the GP, AAMR more than doubled among most groups with MBD—rising over 200% among B, W, and NH individuals, and doubling among H. These findings underscore a widening mortality gap and highlight the urgent need for targeted interventions addressing disparities in breast cancer outcomes among those with MBD. Citation Format: A. Al-Zubaidi, E. Cohen, G. Whitman, B. Adrada, T. Moseley, A. Robinson. Disparities in Breast Cancer Mortality Among Individuals with Mental and Behavioral Disorders: A 25-year population-Based Analysis abstract. In: Proceedings of the San Antonio Breast Cancer Symposium 2025; 2025 Dec 9-12; San Antonio, TX. Philadelphia (PA): AACR; Clin Cancer Res 2026;32(4 Suppl):Abstract nr PS4-09-21.