Abstract
BACKGROUND: Colorectal cancer (CRC) frequently metastasizes to the liver and lungs, leading to poor prognosis. Advances in chemotherapy, minimally invasive surgery, and perioperative care have expanded adjuvant chemotherapy (AC) regimens and eligibility for AC. However, the impact of AC after curative resection of distant metastases on recurrence and prognosis remains uncertain. This study evaluated the role of AC in CRC liver and lung metastases, focusing on cases with curative resection based on the latest studies published in the past five years. METHODS: This systematic review followed PRISMA guidelines. Literature searches of Medline and Cochrane Library (2019-2023) identified studies on AC or observation after curative resection of CRC metastases, reporting outcomes such as overall survival (OS) and disease-free survival (DFS). Data analysis was performed using Review Manager and R software, with results expressed as hazard ratios (HR) and 95% confidence intervals (CI). RESULTS: Seven studies met the eligibility criteria, including one randomized controlled trial and six retrospective studies, encompassing 1580 patients who underwent curative resection (R0) for CRC metastases. This meta-analysis showed a positive trend in OS for the AC group compared to that for the surgery-alone group (HR 0.86, 95% CI: 0.73-1.01; p = 0.06), but the difference was insignificant. AC significantly improved DFS (HR 0.81, 95% CI: 0.66-0.99; p = 0.04). Subgroup analysis indicated that AC significantly improved DFS and tended to improve OS for liver metastasis. In contrast, AC did not improve OS in cases of lung metastasis. CONCLUSIONS: This meta-analysis suggests that AC demonstrated significant positive effects on DFS. Moreover, AC could contribute to improvements in OS. These findings, supported by the latest research, reinforce the recommendation of AC as a valuable strategy for improving both recurrence and survival outcomes in patients with curatively resected distant CRC metastases.