Socioeconomic and geographic disparities in germline genetic testing for Korean male breast cancer

Introduction: Male breast cancer (MBC) accounts for <1% of all breast cancers. Germline genetic testing (GT) is recommended for all MBC patients for treatment and family risk assessment. In Korea, reimbursed GT initially focused on BRCA1/2 then expanded to multigene panel testing (MGPT) in 2017. Nationwide data demonstrate a 2.6-fold increase in MGPT utilization from 2019 to 2023; however, 89.7% of tests were performed in tertiary centers raising concerns about equitable access. We aimed to examine time trends in GT utilization and quantify socioeconomic and geographic disparities in access among Korean MBC patients. Methods: We assessed time trends, determinants and survival outcomes according to GT receipt using the Cancer Public Library Database in K-CURE (Korea-Clinical data Utilization network for Research Excellence), a nationwide registry linking cancer incidence, insurance claims, and mortality data. Total of 774 MBC cases (ICD-10 C50) diagnosed between 2014 and 2019 were identified after applying a 2-year washout period, with follow-up available through 2021. GT was defined as BRCA or MGPT within 12 months of diagnosis. Time trends and associated factors (income level, hospital type, and region) of GT receipt was evaluated. Survival according to GT receipt was explored using Cox proportional hazards models with propensity score matching and inverse probability weighting. Results: Overall, 360 patients (46.5%) received GT, and the proportion undergoing testing increased significantly from 7.0% in 2014 to 68.9% in 2021 (p<0.001). This trend was driven predominantly by BRCA testing, which accounted for 92.3% of the overall increase, whereas MGPT contributed only 7.7%. GT receipt was significantly lower among medical aid recipients than among patients in the highest income quintile (20.0% vs. 51.4%, p<0.01), and in small hospitals compared to tertiary centers (25.0% vs. 52.6%, p<0.01). Geographic centralization was prominent that 42.8% of GT was performed in Seoul, among them 48.0% were non-Seoul residents. Higher income (p=0.013) and residence in Seoul (p=0.023) were independently associated with higher GT receipt, while hospital type was not significant (p=0.087) in multivariable models. For overall survival (OS), GT receipt was associated with improved OS [adjusted HR 0.55 (95% CI 0.36-0.83); p<0.01]. Conclusion: Despite sustained increases in GT utilization, marked socioeconomic and geographic disparities in access indicate that precision oncology for Korean MBC remains inequitable. These findings highlight gaps between national reimbursement policies and the real-world delivery of guideline-concordant care. Further targeted interventions to reduce income- and region-based barriers to GT would be needed. (This study was supported by grants from the National Cancer Center, Korea Grant No. NCC2410821 & NCC2510430)