Survival Outcomes and Prognostic Factors in Patients with Metastatic Colorectal Cancer Treated First-Line mFOLFOXIRI Plus Bevacizumab: A Real-World Study in Vietnam.

(m)FOLFOXIRI plus bevacizumab has improved outcomes in selected patients with metastatic colorectal cancer (mCRC), but data from Southeast Asia remain limited. This study evaluated survival outcomes and factors associated with progression-free survival (PFS) and overall survival (OS) among Vietnamese patients with mCRC receiving first-line mFOLFOXIRI plus bevacizumab. In this retrospective real-world cohort study, 76 patients with mCRC treated with first-line mFOLFOXIRI plus bevacizumab were included. Tumor response, early tumor shrinkage (ETS), depth of response (DpR), PFS and OS were assessed. Survival outcomes were estimated using the Kaplan-Meier method, and exploratory prognostic factors were analyzed using Cox proportional hazards models. A total of 76 patients were included, with a median age of 59.5 years; 61.8% were male, 65.8% had left-sided tumors, and 46.1% had metastases in ≥2 organs. The objective response rate (ORR) was 73.7%, and the disease control rate (DCR) was 97.4%. ETS was achieved in 56.6% of patients, with a median DpR of 40.0%. Molecular profiling showed RAS mutations in 49.3%, BRAF V600E in 5.5%, and PIK3CA mutations in 9.6%. Median PFS was 14.9 months (95% CI, 10.3-19.4), and median OS was 27.0 months (95% CI, 12.4-41.7), with 12- and 24-month OS rates of 81.8% and 56.3%, respectively. In multivariable analysis, ETS remained independently associated with improved PFS (HR 0.36, 95% CI 0.19-0.67; P = 0.001) and OS (HR 0.25, 95% CI 0.11-0.61; P = 0.002). High tumor burden (≥2 metastatic organs) was independently associated with shorter PFS, while elevated baseline CA19-9 was independently associated with inferior OS. In this Vietnamese retrospective real-world cohort, first-line mFOLFOXIRI plus bevacizumab achieved clinically meaningful response and survival outcomes. ETS was independently associated with improved survival and may serve as a useful prognostic indicator.