2177 - Impact of Race/Ethnicity on Receiving Post-Mastectomy Reconstruction and Proton Radiation

A. Yalamanchili¹, G. E. Naoum², A. Ho³, and J. B. Strauss¹; ¹Department of Radiation Oncology, Northwestern University Feinberg School of Medicine, Chicago, IL, ²Northwestern University McGaw medical Center, Chicago, IL, ³Northwestern University Feinberg School of Medicine, Chicago, IL

Purpose/Objective(s): Racial disparity and equity in access to care is a persistent health problem. For breast cancer patients undergoing mastectomy, it remains unclear if there is a discrepancy between different racial and ethnic groups in terms of the offered reconstruction options and different postmastectomy radiation (PMRT) modalities, namely protons. Therefore, we aim to analyze different patterns of postmastectomy treatments among different racial/ethnic groups in a large tertiary care center with the single proton center in the state and serving two neighboring states with no proton centers. Materials/

Methods: We reviewed 509 patients treated with mastectomy at our institution from 2011-2022. Only patients receiving PMRT with or without reconstruction were included. Reconstruction options included single stage direct-to-implant (DTI), two stages expander/implant (TE/I) and autologous flaps. PMRT was delivered with either protons or photons using conventional fractionation 1.8-2 Gy/ fraction to a total dose: 45-50.4 with or without a scar boost. Whenever proton beams were used, the institutional RBE standard was set to 1.1. Reconstruction complications were also recorded and reviewed by two physicians. Multivariable logistic regression models were used to assess the difference in practice patterns for different racial/ethnic groups. For the subgroup who received reconstruction, we also aimed to assess if race/ethnicity was an independent predictor for reconstruction complications.
Results: After applying inclusion criteria, 339 patients were analyzed with an overall median follow up of 4.1 years. 80% of patients identified as white, 3.5% as African-American, 9% as Hispanic, 6% Asian, 1.5% Pacific Islander, and 0.6% others. Among 239 patients receiving reconstruction, 80% were white and 20% were non-white. Similarly, among 100 patients not receiving reconstruction, 77% were white with the remaining 23% as non-white. Rates of white vs non-white patients in receiving reconstruction were not significantly different (OR: 0.79, p=0.43). For those receiving DTI implant reconstruction, 29% were non-white while 17% of those receiving TE/I were non-white. Among Protons patients (n=85), 23% were non-white and similarly in photons patients (n=254), 19% were non-white (p=0.4). On multivariable level, race was not a significant predictor for development of reconstruction complications (OR: 1.33, p=.39).
Conclusion: While our institution has the only proton center in the state serving two neighboring states without proton centers, the majority of patients treated in this cohort were white only. This questions disparities and equity in access to advanced facilities. This cross-sectional study did not show that race/ethnicity within the same advanced health system influences the care received including Proton usage or reconstruction options after mastectomy. National studies are needed to assess access of care for advanced facilities among different racial/ethnic groups.