Impact of medical oncologist certification on survival outcomes in metastatic colorectal cancer: evidence from the SCRUM-Japan MONSTAR-SCREEN Observational Study.

Board certification in surgical oncology improves cancer outcomes, but the impact of medical oncologist certification on systemic therapy outcomes is unknown. We investigated whether the Japanese Society of Medical Oncology (JSMO) board certification of the enrolling physician was associated with treatment quality and survival. This retrospective cohort study used data from the SCRUM-Japan MONSTAR-SCREEN observational study, a nationwide multicenter genomic screening program enrolling patients from 2019 to 2022. Standard treatment implementation rates were compared across cancer types as a secondary outcome.

The primary outcome was overall survival (OS) in patients with metastatic colorectal cancer (mCRC) using Kaplan-Meier analysis and Cox proportional hazards regression with sequential adjustment for clinical and molecular covariates. Among 2,184 patients, standard treatment rates were comparable between board-certified and non-board-certified groups (97.0% vs. 96.9%). In 358 patients with mCRC, enrollment by a board-certified physician was associated with longer OS (median, 36.5 vs. 30.7 months; hazard ratio (HR): 0.66, 95% CI 0.50-0.87; log-rank p = 0.003) even after adjustment for age, sex, tumor sidedness, region, trial participation, molecular targeted therapy, metastatic organ count (HR, 0.73; 95% CI 0.55-0.97; p = 0.029), and after additional adjustment for RAS and BRAF V600E status (HR, 0.64; 95% CI 0.47-0.88; p = 0.005). Board-certified physicians used molecular targeted therapy more frequently (89.5% vs. 80.4%; p = 0.036).

JSMO board certification was independently associated with improved OS in mCRC despite comparable guideline adherence, suggesting that specialist expertise extends beyond treatment selection.