2648 - Disparities in Radiation Treatment of Breast Cancer Brain Metastases
Presenter(s)
T. Pathmarajah1, Y. Gokun2, S. J. Daniel3, B. Slover2, M. Mestres-Villanueva3, J. M. Eckstein3, G. M. Sizemore4, H. LeFebvre5, J. C. Grecula6, R. Raval3, R. Singh3, S. Zhu7, D. M. Blakaj8, A. Chakravarti9, J. D. Palmer3, D. Stover10, N. Williams11, S. R. Jhawar3, and S. Beyer3; 1The Ohio State University College of Medicine, Columbus, OH, 2Center for Biostatistics, Department of Biomedical Informatics, The Ohio State University Wexner Medical Center, Columbus, OH, 3Department of Radiation Oncology, The Ohio State University Wexner Medical Center, Columbus, OH, 4The Ohio State University James Cancer Hospital Department of Radiation Oncology, Columbus, OH, 5The Ohio State University Comprehensive Cancer Center, Division of Medical Oncology, Columbus, OH, 6Department of Radiation Oncology, James Cancer Hospital/Wexner Medical Center, The Ohio State University, Columbus, OH, 7University of Florida, Gainesville, FL, 8Department of Radiation Oncology, James Cancer Hospital, The Ohio State University, Columbus, OH, 9The Ohio State University Comprehensive Cancer Center, Columbus, OH, 10The Ohio State University Medical Center, Columbus, OH, 11The Ohio State University Wexner Medical Center, Columbus, OH
Purpose/Objective(s): Radiation therapy (RT) is important in the multi-disciplinary treatment of breast cancer (BC) brain metastases (BM). Whole brain radiation therapy (WBRT) increases intracranial control with risk of neurocognitive decline. Stereotactic radiosurgery (SRS) is preferred in “limited” BM with excellent local control and less toxicity. We hypothesized that disparities in RT treatment patterns may exist among patients with BC BM.
Materials/Methods: Patients with BC BM diagnosed between 2010-2020 were identified in the National Cancer Database (NCDB). The cohort was divided into patients with RT vs. no RT. Patients were further evaluated between WBRT vs. SRS. We fitted Overlap Propensity Score Weighting (OPSW) Cox models to account for confounding between OS and RT. Time-varying receipt of RT was used because the proportionality assumption was not met. Variables included in the propensity score model included age, race, ethnicity, Charlson-Deyo score (CDS), insurance, residence, molecular subtype, facility type as well as chemotherapy, immunotherapy and hormone therapy.
Results: Of 8,909 patients with BC BM, 3,864 (43.4%) received RT (74.1% with WBRT and 25.9% with SRS) and 5045 (56.6%) did not receive RT. Median age in the cohort was 61 yo (IQR: 52-69)) and most patients were white (76.6%) with CDS 0 (80.1%). Median follow-up was 9.8 months. Patients with brain RT relative to no RT were more likely to be younger (median 60 vs. 62 yo, p<0.001) with private insurance (40.8 vs. 35.3%, p<0.001), triple-negative subtype (23.1 vs. 16.1%, p<0.001) and received chemotherapy (65.4 vs. 46.6%, p<0.001) or immunotherapy (22.4 vs. 15.2%, p<0.001). Of patients with RT, white patients (78.5 vs. 76.3%, p=0.013) with higher income (30.7 vs. 26.4%, p=0.007) and treatment at academic facilities (40.4 vs. 32.9%, p<0.001) were more likely to undergo SRS vs. WBRT. African American patients (19.4 vs. 16.4%, p=0.013) with lower income (18.2 vs. 14.5%, p=0.007), urban location (14.2 vs. 10.9%), p=0.020), triple negative subtype (24.2 vs. 20.0%, p=0.05) and community treatment facilities (39.2 vs. 34.9%, p<0.001) were more likely to receive WBRT vs. SRS. Median OS for the entire cohort was 10.9 mo (95% CI: 10.4-11.5) and for RT cohort was 12.7 mo (95% CI: 11.9-13.6). On MVA when adjusting for systemic therapies (chemotherapy, immunotherapy, hormone therapy), receipt of brain RT did not reach significance for reduced mortality risk. Patients who received chemotherapy were associated with 48% lower hazard of mortality compared to those who did not (aHR: 0.52, 95% CI: 0.49-0.56). Among patients who received RT, SRS was associated with better OS vs. WBRT (aHR: 0.76, 95% CI: 0.69-0.83) on MVA.
Conclusion: Among patients with BC BM, RT was associated with younger age and private insurance. Among those who received RT, SRS varied based on race, income, subtype, and facility. Our study suggests that variations in brain RT patterns may be associated with mortality risk and identifies potential disparities among patients with BC BM.