2934 - Surgery and Adjuvant Radiation are Associated with Improved Overall Survival Relative to Systemic Therapy Alone in Metastatic Inflammatory Breast Cancer (MIBC)
Presenter(s)
J. M. Eckstein1, Y. Gokun2, S. Obeng-Gyasi3, D. Stover4, T. Y. Andraos1, R. Young1, S. Beyer1, and S. R. Jhawar1; 1Department of Radiation Oncology, The Ohio State University Wexner Medical Center, Columbus, OH, 2Center for Biostatistics, Department of Biomedical Informatics, The Ohio State University Wexner Medical Center, Columbus, OH, 3Ohio State University, Columbus, OH, 4The Ohio State University Medical Center, Columbus, OH
Purpose/Objective(s): Despite local control benefits, local therapy to the primary site of disease has not been shown to improve overall survival (OS) in non-inflammatory metastatic breast cancer. Given the increased incidence and morbidity of local recurrence with MIBC, we hypothesized that improved local control from modified radical mastectomy (MRM) and radiation therapy (RT) may translate into an OS benefit when added to systemic therapy in the MIBC population.
Materials/Methods: All patients diagnosed with MIBC from 2010 to 2020 were identified in the NCDB. The cohort was divided into groups who received systemic therapy only, systemic therapy followed by MRM (bimodality therapy-BMT), and systemic therapy followed by MRM followed by adjuvant RT to the chest wall and/or regional lymph nodes (trimodality therapy-TMT). The BMT group was set as the reference. Propensity score weighted Cox proportional hazard models were fitted based on age, molecular subtype, and number of metastases (solitary or multiple). Subset analysis comparing BMT to TMT was done based on pathologic response to systemic therapy (any response versus no response).
Results: A total of 2950 patients met inclusion criteria, including 409, 258, and 2283 in the TMT, BMT and systemic therapy only groups, respectively. Patients in the TMT group were younger vs the BMT and systemic therapy only groups (median age 54 vs 59 vs 58). The TMT group was most likely to have a solitary metastasis (91.7%), relative to the BMT therapy (81.8%) and systemic therapy (67.6%) groups. Compared with BMT, systemic therapy only treatment had an increased risk of death (aHR 1.89, 95% CI: 1.57-2.28). TMT patients had a decreased risk of death (HR 0.81, 95% CI: 0.67-0.98) compared to the BMT cohort on crude analysis, but in the adjusted model this became not significantly different (aHR 0.95, 95% CI 0.74-1.21). 474 patients had pathologic response data available. In 423 patients who demonstrated any response to systemic therapy, receipt of TMT vs BMT was not associated with OS (aHR 0.96, 95% CI 0.72-1.29). In 51 patients without any pathologic response, TMT was associated with improved OS (aHR 0.47, 95% CI 0.24-0.92) adjusting for age and number of metastases.
Conclusion: In this retrospective review of MIBC in the NCDB, TMT and BMT were associated with improved OS relative to systemic therapy alone. In the overall cohort, OS was similar between BMT and TMT, but TMT was associated with improved OS among patients that did not demonstrate a pathologic response to systemic therapy at the time of surgery. More work is needed to understand the OS impact of local therapies to the breast and lymph nodes in MIBC.