Abstract Background: In older adults with early-stage breast cancer, clinical decisions must weigh the benefits of systemic therapy against age-related comorbidities and competing causes of death. We assessed age-stratified treatment patterns and outcomes in a Jordanian cohort, where national life expectancy approximates 75 years. Methods: We retrospectively analyzed 716 women aged ≥60 years with stage I-III hormone receptor-positive, HER2-negative early breast cancer treated at King Hussein Cancer Center (2015-2021). Patients were grouped as follows: 328 (45.8%) aged 60-65 years, 296 (41.3%) aged 66-74 years, and 92 (12.8%) aged ≥75 years. We compared tumor features, systemic therapy use, and survival. Kaplan-Meier methods estimated overall survival (OS) and breast cancer-specific survival (BCSS). Causes of death were classified as breast cancer-related or non-cancer-related. Results: Tumor characteristics were comparable across age groups. Most patients (91.9%) had ER-high tumors, and grade 2 histology predominated (62.6%). Clinical T and N stages, including cT2 tumors (52.5%) and cN+ nodal status (39.1%), were similarly distributed. Use of chemotherapy decreased significantly with age: 70.7% in those aged 60-65, 50.0% in 66-74, and 10.9% in ≥75 (P .001). In contrast, endocrine therapy was nearly universal across all groups (97%), with aromatase inhibitors used in 79.4% and tamoxifen in 17.9%. Among patients receiving endocrine therapy, 51.8% completed or exceeded 5 years of treatment, while 14.4% relapsed before 5 years. The median follow-up was 66.7 months. Five-year BCSS remained high across age groups, at 96.2%, 94.2%, and 91.8% for patients aged 60-65, 66-74, and ≥75 years, respectively, with no significant difference (P = .40). However, 5-year OS declined significantly with age: 91.1%, 88.8%, and 78.0%, respectively (P = .0012). Breast cancer-related mortality was relatively stable across age groups, occurring in 7.6%, 9.1%, and 9.8% of patients aged 60-65, 66-74, and ≥75 years, respectively. while non-cancer-related mortality significantly increased: 6.1%, 10.1%, and 18.5% (P = .005), contributing substantially to the decline in OS among the oldest patients. There was a statistically significant difference in the distribution of causes of death across age groups (P = .005). Non-breast cancer-related mortality increased notably with age, occurring in 6.1%, 10.1%, and 18.5% of patients aged 60-65, 66-74, and ≥75 years, respectively, accounting for 67 deaths (9.4%) overall. In comparison, breast cancer-related deaths were relatively stable across age groups, occurring in 7.6%, 9.1%, and 9.8% of patients in the same age categories, totaling 61 deaths (8.5%) in the cohort. Conclusions: In our cohort, the decline in overall survival among patients aged ≥75 years was primarily driven by non-cancer-related mortality, rather than deaths from breast cancer. Despite this, breast cancer-specific survival remained excellent in this age group, even with markedly reduced use of chemotherapy. These findings support age-tailored treatment strategies that allow for safe de-escalation of systemic therapy while preserving oncologic outcomes, with careful consideration of national life expectancy in treatment planning. Citation Format: F. Tamimi, M. Horani, T. Al-Batsh, O. El Khatib, B. Sharaf, Y. Al-Masri, A. Ghanem, Q. Jawarneh, M. AL-yag'oub, A. Jaffal, R. Khader, S. Abdel-Razeq, A. Alanani, M. El-Atrash, M. Abunasser, H. Abdel-Razeq. Impact of Competing Mortality on Survival Outcomes in Patients Aged ≥75 With HR+/HER2- Early Breast Cancer 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 PS3-09-24.
Tamimi et al. (Tue,) studied this question.