FOLFOXIRI Versus Doublet Regimens in Right-Sided Metastatic Colorectal Cancer: Focus on Subsequent Therapies and Impact on Overall Survival

Introduction: It has been determined that right-sided metastatic colorectal cancer (mCRC) has a worse prognosis for overall survival (OS). Currently, there is no consensus on the best systemic regimen for treatment-naive right-sided tumors. We compared the impact of subsequent therapies on OS of patients treated with FOLFOXIRI (leucovorin, 5-fluorouracil, oxaliplatin, irinotecan) versus doublet regimens. Patients and Methods: Data of patients with treatment-naive right-sided mCRC who received FOLFOXIRI or doublet regimens between January 2001 to December 2018 were retrospectively analyzed. OS was compared between the two groups, and prognostic factors were assessed by multivariate analysis. Results: A total of 196 patients were selected; 33 patients received FOLFOXIRI and 163 patients doublet therapy. Median follow-up was 82.3 months. The FOLFOXIRI cohort received fewer subsequent lines of therapies (61% vs. 78%, P = .043). The greater the number of subsequent lines of therapy, the lower the risk of death (hazard ratio [95% confidence interval] 0.67 [0.46-0.99], 0.62 [0.45-0.86], and 0.56 [0.39-0.81] for > 1, > 2, and > 3 lines, respectively). By multivariate analysis, metastasectomy and bevacizumab with subsequent lines of therapy were the variables with greatest positive impact on OS (respectively, hazard ratio [95% confidence interval] 0.54 [0.38-0.78] and 0.61 [0.44-0.84]). Conclusion: Patients with treatment-naive right-sided mCRC who received front-line FOLFOXIRI had a lower number of subsequent therapies than patients who received doublet regimens. Our findings highlight the relevance of the continuum of care in mCRC, regardless of the first-line regimen, and the importance of careful selection of patients for the FOLFOXIRI regimen.