Prognostic impact of RAS/BRAF mutations and clinical factors in 441 patients undergoing pulmonary metastasectomy for colorectal cancer.

214 Background: Pulmonary metastasectomy (PM) is a curative treatment option for colorectal cancer (CRC) patients with lung metastases. While several clinical and molecular factors such as RAS / BRAF mutations (MTs) have been reported as poor prognostic markers, few large-scale studies have comprehensively assessed these variables. Methods: We retrospectively analyzed 441 CRC patients who underwent PM at our hospital between January 2015 and December 2024. Follow-up continued until April 30, 2025. Clinical and molecular data were collected, including age, sex, performance status (PS), smoking history, resection type, primary tumor location, RAS / BRAF V600E MTs status, the number and size of lung metastases, and preoperative carcinoembryonic antigen (CEA) levels. Disease-free survival (DFS) and overall survival (OS) were estimated using the Kaplan–Meier method. Prognostic factors were evaluated using univariate and multivariate Cox proportional hazards models. Results: Among 441 patients, median DFS was 31.0 months (95% CI: 19.0-not reached), and median OS was not reached (19.0-NR). RAS / BRAF V600E MTs status was assessed in 347 patients; RAS / BRAF wild type (WT): n=157 (45.2%), RAS MTs: n=184 (53.0%; KRAS : n=173, NRAS : n=11), BRAF V600E MTs: n=6 (1.7%). Median DFS was 22.8 months (14.2-NR) in WT, 31.0 months (13.2-NR, HR: 0.97, 95% CI, 0.72-1.30, p=0.83) in RAS MTs, 9.5 months (2.9-44.7, HR: 2.65, 1.15-6.13, p=0.023) in BRAF V600E MTs; median OS was not reached (19.0-NR), 98.6 months (83.2-NR, HR: 1.43, 0.88-2.30, p=0.15), 37.8 months (20.9-NR, HR: 7.52, 2.54-22.3, p