Abstract P1-10-10: Radiation Treatment Patterns for Elderly Women with Breast Cancer Brain Metastases

Abstract

Abstract Background Breast cancer is the second most common cause of brain metastases (BM). Despite increasing incidence of BM in elderly patients, there is limited data on the optimal management of BM in this age group. In this study, we assessed the survival outcomes and treatment patterns of elderly breast cancer patients with BM (≥ 65 yo) treated at our institution and compared them to younger patients. Methods An IRB-approved single-institutional review of biopsy-proven breast cancer patients with BM treated with 1 to 5-fraction stereotactic radiation therapy (SRT) from 2015 to 2020 was performed. Primary endpoint was intracranial progression free survival (PFS) defined as time interval between end of SRT to date of first CNS progression. Secondary endpoints were overall survival (OS) from end of SRT, and radiation treatment patterns. Kaplan-Meier estimates, and Cox proportional hazard regression method were used for survival analyses. SPSS v26.0 was used for statistical analysis and p-value < 0.05 was considered significant. Results A total of 115 metastatic breast cancer patients with BMs were included of which N=29 were ≥65 yo and N=86 were < 65 yo. They received a total of 43 and 143 courses of stereotactic linac-based radiation therapy (RT) respectively to a mean number of 4.3 BM lesions (range 1-22). Median age at RT was 70 years (range 65-84) compared to 50.5 years (31-64) in younger patients. About 55.2% of elderly patients were ER/PR positive/Her2 negative (vs 24.4% in younger cohort), 31% were Her2 positive (vs 41.9%) and 13.8% were triple negative (vs 33.7%). Among patient characteristics, there was significant difference among elderly and young patients in hormone receptor status (p = 0.016); CNS only oligometastatic disease (0% vs 11.2%, p = 0.005); and the presence of extracranial disease at SRS (97.7% vs 79.7%, p < 0.001). There was no significant difference between the two age groups in Karnofsky performance score (KPS) (62.7% vs 45.5% with KPS ≤ 80, p = 0.131), number of brain lesions treated (23.2% vs 30.1% with ≥ 5 BMs, p = 0.445), number of patients receiving prior whole brain radiotherapy (WBRT) (10.3% vs 19.8%, p = 0.062), surgery (23.2% vs 30.1%, p = 0.592), systemic therapy (including chemotherapy, targeted therapy and endocrine therapy) after SRT (86% vs 86.7%, p = 0.543), and salvage WBRT (10.3% vs 19.8%, p = 0.134). Median OS after RT was poorer in patients ≥ 65 yo compared to younger patients (7.9 months vs 14.4 months, p = 0.020), while intracranial PFS from RT was similar (8.5m vs 6.5m, p =0.345). The rates of freedom from neurological death and leptomeningeal disease (LMD) at 1 year were similar between the two groups (83.3% vs 87%, p = 0.780 and 87.6% vs 73.3%, p = 0.627, respectively). On univariate analysis, significant predictors of survival were age ≥65 yo (hazard risk, HR = 1.56), KPS < 80 (HR = 1.69), extracranial progression at RT (HR = 2.44), systemic therapy after RT (HR = 0.28) and LMD (HR = 1.57). On multivariate analysis, age was not a significant factor for survival after adjusting for KPS, extracranial progression and systemic therapy. Conclusions Although elderly women had poorer OS than younger women, OS was similar after adjusting for KPS, extracranial progression and systemic therapy; and there was no difference in rates of intracranial PFS, neurological deaths and LMD in the different age groups. This study suggests that age alone may not play an independent role in treatment-selection and outcomes for breast cancer patients with BMs and personalized decision making including other clinical factors should be considered. Future studies are warranted to assess neurocognitive outcomes and other radiation treatment toxicities in elderly patients. Citation Format: Rituraj Upadhyay, Haley K. Perlow, Nicole Williams, Brett Klamer, Julia White, Jose G. Bazan, Sachin R. Jhawar, Dukagjin M. Blakaj, John Grecula, Andrea Arnett, Evan Thomas, Arnab Chakravarti, Raju R. Raval, Maryam Lustberg, Joshua Palmer, Sasha Beyer. Radiation Treatment Patterns for Elderly Women with Breast Cancer Brain Metastases [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr P1-10-10.