Optimal duration of therapy in the first line treatment of metastatic colorectal cancer: single center experience

Background / Aim. FOLFOX (5fluorouracil, folinic acid, oxaliplatin)/CapOx (capecitabine, oxaliplatin) plus bevacizumab and FOLFIRI (5 fluorouracil, folinic acid, irinotecan) plus bevacizumab are a standard treatment options for a first line treatment of metastatic colorectal carcinoma (mCRC). The aim of this study was to compare overall response rate (ORR), progression-free survival (PFS) and overall survival (OS) in the groups of patients with mCRC who were treated in the first line with FOLFIRI/bev versus FOLFOX/bev. At the same time, it was compared the safety profile in observed groups of patients and investigated optimal treatment duration and characteristics of patients who had the best treatment outcomes. Methods. In a retrospective-prospective study, patients with mCRC were treated with a chemotherapy protocols for the first line in combination with bevacizumab (FOLFOX/bev, respectively, FOLFIRI/bev). Treatment efficacy was evaluated on the basis of overall response rate (ORR), progression-free survival (PFS) and overall survival (OS), and the safety of treatment was evaluated by monitoring adverse drug reactions. Results. ORR was 70% in the FOLFIRI/bev group and 50% in the FOLFOX/bev group. Median PFS for FOLFIRI/bev (n = 30) and for FOLFOX/bev (n = 30) was 15.6 months and 12.1 months respectively (HR, 0.85; 95% confidence interval (CI) 0.47-1.53; P = 0.5591). Median OS for FOLFIRI/bev and for FOLFOX/bev was 24.7 months and 19.9 months respectively (HR, 0.67; 95% confidence interval (CI) 0.37-1.23; P = 0.1552). In both patient groups, the patients who received more than 9 cycles of induction therapy had better treatment response in comparison with patients who received less than 9 cycles of therapy. In FOLFOX/bev group PFS was 16.9 versus 9.7 months and OS was 22.1 versus 17.6 months respectively. In FOLFIRI/bev group PFS was 9 months for patients who received less than 9 cycles of therapy versus 18.8 months for patients who received more than 9 cycles, OS was 18.0 versus 27.7 respectively. The adverse drug reactions grade 3 and 4 were 7% in the FOLFIRI/bev group versus 27% in the FOLFOX/bev group. Conclusion. Patients who received FOLFIRI/bev had better ORR (70 % versus 50 %), PFS (15.6 versus 12.1 months) and OS (24.7 versus 19.9 months). In both patient groups, better treatment response had the patients who received induction therapy for 4-6 months (more than 9 cycles of therapy).