Abstract
PURPOSE: Wild-type unresectable metastatic colorectal cancer (mCRC) poses challenges for treatment optimization. Effective first-line targeted therapies are crucial for improving outcomes, particularly when combined with second-line oxaliplatin-based chemotherapies. This study examined the effects of first-line cetuximab+FOLFIRI versus bevacizumab+FOLFIRI, followed by second-line oxaliplatin-based chemotherapy, on survival among patients with KRAS wild-type mCRC without primary tumor resection (PTR). METHODS: A retrospective analysis of Taiwanese data (2013-2019) included patients with KRAS wild-type unresectable mCRC who received first-line cetuximab+FOLFIRI or bevacizumab+FOLFIRI, followed by second-line oxaliplatin-based chemotherapy. Survival outcomes-overall survival (OS) and time to treatment discontinuation (TTD)-were compared between these regimens using stabilized inverse probability of treatment weighting to adjust for potential confounders, followed by multivariate Cox proportional hazards regression analysis to account for clinical and biological variables. RESULTS: In patients without PTR, first-line cetuximab+FOLFIRI with second-line oxaliplatin-based chemotherapy significantly improved OS from the start dates of first- and second-line treatment compared to first-line bevacizumab+FOLFIRI with second-line oxaliplatin-based therapy, yielding adjusted hazard ratios (HRs) of 0.60 (95% confidence interval [CI], 0.46-0.78) and 0.56 (95% CI, 0.42-0.73), respectively. No significant difference in TTD was observed (HR, 0.82; 95% CI, 0.65-1.04). CONCLUSIONS: First-line cetuximab+FOLFIRI followed by second-line oxaliplatin-based chemotherapy offers superior OS compared to bevacizumab+FOLFIRI followed by second-line oxaliplatin‑based chemotherapy in KRAS wild-type mCRC without PTR. These findings underscore the importance of personalized treatment sequencing, highlighting the need for further research to optimize mCRC management.