Oncologic effects of adjuvant chemotherapy in patients with ypT0-2N0 rectal cancer after neoadjuvant chemoradiotherapy and curative surgery: A meta-analysis

Purpose: The role of adjuvant chemotherapy for patients with ypT0-2N0 rectal cancer following neoadjuvant chemoradiotherapy (nCRT) and curative surgery is uncertain. We performed a meta-analysis using selected studies to compare adjuvant chemotherapy with observation for this cohort of patients. Methods: PubMed, Embase, and the Cochrane Library were searched. Data were pooled, and overall effect size was calculated using random effect models. Outcome measures were 5-year overall survival (OS), disease-free survival (DFS), local, and distant recurrence. Results: We included 17 nonrandomized studies for qualitative analysis and 16 nonrandomized studies that examined 4,747 patients for the meta-analysis. In analysis of patients with ypT0N0 rectal cancer, adjuvant chemotherapy had no significant effect on OS (odds ratio [OR], 1.53; 95% confidence interval [CI], 0.86-2.72; I2 = 27%), DFS (OR, 1.22; 95% CI, 0.61-2.42; I2 = 5%), local recurrence (OR, 0.78; 95% CI, 0.08-7.37; I2 = 0%), and distant recurrence (OR, 1.04; 95% CI, 0.41-2.62; I2 = 0%). In analysis of patients with ypT1-2N0 rectal cancer, adjuvant chemotherapy also had no significant effect on OS (OR, 2.15; 95% CI, 0.59-7.80; I2 = 26%), DFS (OR, 1.66; 95% CI, 0.35-7.85; I2 = 44%), local recurrence (OR, 2.56; 95% CI, 0.72-9.13; I2 = 0%), and distant recurrence (OR, 1.15; 95% CI, 0.23-5.87; I2 = 0%). Conclusion: Adjuvant chemotherapy may have no oncologic benefits in patients with ypT0-2N0 rectal cancer after nCRT and radical surgery. Routine use of adjuvant chemotherapy for those patients may be avoided.