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; I(2) = 27%), DFS (OR, 1.22; 95% CI, 0.61–2.42; I(2) = 5%), local recurrence (OR, 0.78; 95% CI, 0.08–7.37; I(2) = 0%), and distant recurrence (OR, 1.04; 95% CI, 0.41–2.62; I(2) = 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; I(2) = 26%), DFS (OR, 1.66; 95% CI, 0.35–7.85; I(2) = 44%), local recurrence (OR, 2.56; 95% CI, 0.72–9.13; I(2) = 0%), and distant recurrence (OR, 1.15; 95% CI, 0.23–5.87; I(2) = 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.