Impact of Irinotecan and Oxaliplatin on Overall Survival in Patients With Metastatic Colorectal Cancer: A Population-Based Study

Purpose: In the past 10 years, the number of available therapeutic options for patients with metastatic colorectal cancer (MCRC) has expanded from fluorouracil (FU)-based therapy to include irinotecan and oxaliplatin. The temporal impact of these advances on the overall survival of a population-based cohort will be evaluated. Patients and Methods: Cohort A from years 1995 to 1996 was chosen to represent FU-based chemotherapy. In 2000 and in 2003 to 2004, irinotecan and oxaliplatin respectively became generally available to patients in British Columbia, Canada; cohorts B and C were chosen from these years, respectively. Included were 1,333 patients referred with MCRC (metastatic status, M1) in cohorts A (n = 357), B (n = 268), and C (n = 708). Survival was calculated from time of diagnosis of M1 disease to either death or date of last contact. Results: Cohorts were generally similar; more patients received chemotherapy in cohorts B (62%) and C (62%) compared with cohort A (49%; P < .001). In cohort C, 33% of patients received both irinotecan and oxaliplatin, and 10% of patients received biologic therapies. In cohorts A, B, and C, median overall survival was 9.4, 10.8, and 13.1 months (A v C, P = .002; B v C, P = .022) in all patients, respectively, and 12.6, 14.0, and 17.1 months (A v C, P = .004; B v C; P = .019) in patients treated with chemotherapy, respectively. Improvements between cohorts A and C achieved statistical significance, whereas those between A and B did not. Patients not treated with chemotherapy experienced poor outcomes; this remained unchanged. Conclusion: In this population-based study, a significant prolongation in overall survival was observed in patients with MCRC in the period in which both irinotecan and oxaliplatin were available. Outcomes parallelled those seen in phase III clinical trials.