Patient Selection for Adjuvant Chemotherapy in High-Risk Stage II Colon Cancer: A Systematic Review and Meta-Analysis

OBJECTIVES: Patients with high-risk stage II colon cancer (CC) are recommended to undergo adjuvant chemotherapy (ACT). However, whether such patients can benefit from ACT remains unclear. This meta-analysis aimed to investigate the clinicopathologic parameters that are important for selecting patients for ACT in high-risk stage II CC. METHODS: We systematically retrieved articles from PubMed, the Cochrane Library, and Embase that were published up to September 13, 2018. We analyzed overall survival (OS) and disease-free survival (DFS) based on hazard ratios (HRs) and 95% confidence intervals (CIs). RESULTS: A total of 23 cohort studies and 1 randomized controlled trial were included in our study. Overall analyses showed that ACT improved OS (HR=0.64, 95% CI=0.51-0.80, P<0.001) and DFS (HR=0.46, 95% CI=0.28-0.76, P=0.002) in patients with high-risk stage II CC. Subgroup analyses showed that ACT improved OS in patients with localized intestinal perforation and obstruction and pT4 lesions and improved OS and DFS in patients with <12 sampled lymph nodes. However, ACT had no significant effect on OS in patients with lymphovascular invasion, perineural invasion, or poorly differentiated histology. CONCLUSIONS: Our study suggests that not all high-risk factors (lymphovascular invasion, perineural invasion, poorly differentiated histology) show a benefit from ACT. Randomized controlled trials selectively targeting high-risk patients will need to be conducted in the future.