Standard treatment options for the first-line treatment of metastatic colorectal carcinoma (mCRC) are 5-fluorouracil, folinic acid, oxaliplatin (FOL-FOX4)/capecitabine (CapOx), plus bevacizumab (bev) and 5-fluorouracil, folinic acid and irinotecan (FOLFIRI) plus bev. The aim of this study was to compare overall response rate (ORR), progression-free survival (PFS), and overall survival (OS) in patients with mCRC who were treated in the first line with FOLFIRI/bev vs. FOLFOX4/bev. At the same time, the aim was also to compare the safety profile in the observed groups of patients and to investigate optimal treatment duration and characteristics of patients who had the best treatment outcomes. Methods. The retrospective-prospective study included patients with mCRC treated with chemotherapy protocols for the first line in combination with bev (FOLFOX4/bev, respectively, FOLFIRI/bev). Treatment efficacy was evaluated on the basis of ORR, PFS, and OS, and the safety of treatment was evaluated by moni-toring adverse drug reactions (ADR). Results. ORR was 70% in the FOLFIRI/bev group and 50% in the FOL-FOX4/bev group. Median PFS for FOLFIRI/bev (n = 30) and for FOLFOX4/bev (n = 30) was 15.6 months and 12.1 months, respectively [hazard ratio (HR) 0.85; 95% confi-dence interval (CI) 0.47–1.53; p = 0.5591]. Median OS for FOLFIRI/bev and for FOLFOX4/bev was 24.7 months and 19.9 months, respectively (HR 0.67; 95% CI 0.37–1.23; p = 0.1552). In both patient groups, the patients who re-ceived more than 9 cycles of induction therapy had better treatment response compared with patients who received less than 9 cycles of therapy. In the FOLFOX4/bev group, PFS was 16.9 vs. 9.7 months, and OS was 22.1 vs. 17.6 months, respectively. In the FOLFIRI/bev group, PFS was 9 months for patients who received less than 9 cycles of therapy vs. 18.8 months for patients who received more than 9 cycles, and OS was 18.0 months vs. 27.7 months, re-spectively. ADR grade 3 and 4 had 7% of the patients in the FOLFIRI/bev group vs. 27% in the FOLFOX4/bev group. Conclusion. Patients who received FOLFIRI/bev com-pared to those treated with FOLFOX4/bev had better ORR (70% vs. 50 %, respectively), PFS (15.6 months vs. 12.1 months, respectively), and OS (24.7 months vs. 19.9 months, respectively). In both patient groups, the patients who received induction therapy for 4–6 months (more than 9 cycles of therapy) had a better treatment response.
