Abstract PO3-03-02: Effect of Surgery on Breast Cancer-Specific Mortality in Elderly Patients with Hormone Receptor-Positive, HER2-Negative Breast Cancer

Abstract

Abstract Background: The number of elderly patients with breast cancer has been increasing in Japan. Although standard treatment including surgery is desirable if the expected life expectancy is sufficient, not all elderly patients with breast cancer are eligible for surgery due to frailty and comorbidities. Endocrine therapy (ET) alone is an alternative option if surgery is not considered adequate in patients with hormone receptor-positive breast cancer. We evaluated whether ET alone was associated with inferior overall and breast cancer-specific survival compared to standard treatment including surgery in elderly patients. Methods: This study included all patients aged 75 years and over who were diagnosed with non-metastatic primary invasive hormone receptor-positive, HER2-negative breast cancer and treated at Hiraka General Hospital from July 2006 to March 2022. Patients were divided as those who received ET alone (ET alone group) and those who received surgery with other therapies (Surgery group). Survival status as on March 31, 2023 and cause of death were determined. Overall survival and breast cancer-specific survival were estimated using the Kaplan–Meier method and compared using the log-rank test. Univariate analysis and multivariate Cox proportional hazards regression model including age, Eastern Cooperative Oncology Group performance status (PS) score, clinical stage, and treatment were used to identify survival-associated factors. Propensity score matching was used to reduce the effect of selection bias on treatment type during survival comparison of the groups. Results: The study cohort comprised 128 patients, including 33 and 95 patients in the ET alone group and Surgery group, respectively. The median ages were 84.6 and 80.4 years in the ET alone group and Surgery group, respectively (p < 0.05). Ten patients (30%) in the ET alone group had poor PS (3 or 4), and no patient in the Surgery group had poor PS (p < 0.01). Also, 24.2%, 54.5%, and 21.2% of the patients in the ET alone group and 48.4%, 43.2%, and 8.4% of the patients in the Surgery group had clinical stage I, II, and III disease at diagnosis, respectively (p < 0.05). Survival status was confirmed in all patients, and the cause of death was confirmed in 52 of the 53 patients who died (98%) during the study period, including 24 and 29 patients in the ET alone group and Surgery group, respectively. Breast cancer was the cause of death in 3 patients (13%) in the ET alone group and 5 patients (17%) in the Surgery group. By univariate analysis, overall survival was significantly better in the Surgery group than in the ET alone group (median, 12.5 vs. 4.1 years; p < 0.0001). Similarly, breast cancer-specific survival was better in the Surgery group than in the ET alone group (p < 0.05). By multivariate Cox proportional hazards regression analysis, age was associated with shorter overall survival time (hazard ratio [HR] 1.07, 95% confidence interval [CI] 1.00–1.15; p = 0.04) and surgery was associated with longer overall survival (HR 0.24, 95% CI 0.12–0.47; p < 0.001). Breast cancer-specific survival was associated with age (HR 1.18, 95% CI 1.03–1.36; p = 0.02) and clinical stage (HR 8.89, 95% CI 1.05–75.5; p < 0.05) but not with treatment (HR 0.66, 95% CI 0.73–5.85; p = 0.71). After propensity score matching, overall survival was significantly better in the Surgery group than in the ET alone group (HR 0.26, 95% CI 0.09–0.73; p = 0.01) whereas breast cancer-specific survival was not significantly different between the two groups (HR 0.82, 95% CI 0.08–8.27; p = 0.86). Conclusion: Even in elderly patients, surgery should be considered if sufficient life expectancy is expected. However, most of the deaths were not related to breast cancer in the present study cohort. Therefore, for elderly patients without sufficient life expectancy, endocrine therapy alone would be an appropriate option. Citation Format: Misako Yatsuyanagi, Tomoyuki Shimada, Yuko Takeishi, Yukiko Matsuzaka, Chika ohsawa. Effect of Surgery on Breast Cancer-Specific Mortality in Elderly Patients with Hormone Receptor-Positive, HER2-Negative Breast Cancer [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO3-03-02.