Adjuvant oxaliplatin-based chemotherapy comparing observation alone after radical resection of metachronous metastases of colorectal cancer: interim analysis

Abstract

Introduction. Despite the registered standard treatment option for patients who underwent radical resection for metachronous metastases of colorectal cancer (CRC), the feasibility of adjuvant chemotherapy (ACT) for all patients seems controversial. Due to studies demonstrating improved disease-free survival rates with postoperative chemotherapy vs observation, it would seem that there is reasonable expectation of improved overall survival (OS) rates, which, however, were not statistically different between groups. This article presents the interim results of our own study.Aim. To analyse the efficacy of ACT vs dynamic observation in patients who underwent surgery for metachronous metastases of colorectal cancer.Materials and methods. It was a prospective-retrospective, non-randomized, non-inferiority study. A total of 120 patients were recruited between June 2008 and September 2022. The ACT group included 71 patients. All patients received only oxaliplatin-based chemotherapy regimens; the dynamic observation group included 49 patients.Results. The interim analysis showed that the median disease-free survival (mDFS) in the ACT group (n = 71) was 20.9 months (13.7–28.3) vs 24.4 months in the dynamic observation group (n = 49) (11.1–37.7), HR: 0.76 (95% CI: 0.45–1.29), p = 0.29. Two-year disease-free survival (DFS) rates were 46.6% in the post-surgery chemotherapy (CT) group (n = 50) and 55.5% in the experimental group (n = 31), HR: 0.69 (95% CI: 0.39–1.2), p = 0.21.Conclusion. ACT has not improved the long-term treatment outcomes in patients who underwent radical resection for metachronous metastases of CRC.