Impact of diabetes on breast cancer mortality in elderly female patients: A retrospective analysis (1999–2020)

Breast cancer remains a leading cause of morbidity and mortality among women in the United States. Diabetes mellitus (DM) is also highly prevalent in the elderly female population, and the 2 conditions frequently coexist. National mortality trends in older women with both breast cancer and DM have not been thoroughly explored. We conducted a retrospective analysis of mortality data for women aged ≥65 years with breast cancer and DM using the CDC WONDER database (1999-2020). ICD-10 codes (breast cancer: C50; DM: E10-E14) were used to obtain de-identified patient data. age-adjusted mortality rates and annual percent changes were calculated using Joinpoint regression. Trends were analyzed to identify disparities among age, race/ethnicity, region, and urbanization level. A total of 53,327 deaths occurred in elderly female patients with breast cancer and DM in the United States between 1999 and 2020. The average annual percentage change of 0.3% (95% confidence interval: -0.4-0.9; P = .45). Mortality was highest among women aged >65 years (age-adjusted mortality rate [AAMR]: 20.59). Non-Hispanic (NH) Black women had the highest mortality (AAMR: 16.0), and regionally, the AAMR was highest in the Midwest (AAMR: 11.3). The states with the highest AAMR were the District of Columbia, Ohio, Nebraska, Oklahoma, and West Virginia. Additionally, nonmetropolitan areas had consistently higher AAMR (11.80) compared to metropolitan areas (9.40). Our study demonstrated a stable trend in the DM-related breast cancer mortality in recent years. Several high-risk groups warrant further investigations, including older elderly women (aged > 65), NH black females, the Midwestern population, nonmetro regions, and states in the top 10th percentile (District of Columbia, Ohio, Nebraska, Oklahoma, and West Virginia). Robust targeted policies and healthcare strategies are urgently needed to address disparities and reduce mortality in vulnerable populations.