Total neoadjuvant therapy versus standard therapy in locally advanced rectal cancer: A systematic review and meta-analysis of 15 trials

BACKGROUND: Neoadjuvant chemoradiotherapy (nCRT) before total mesorectal excision (TME) and followed systemic chemotherapy is widely accepted as the standard therapy for locally advanced rectal cancer (LARC). This meta-analysis was to evaluate the current evidence regarding nCRT in combination with induction or consolidation chemotherapy for rectal cancer in terms of oncological outcomes. METHODS: A systematic search of medical databases (PubMed, EMBASE and Cochrane Library) was conducted up to the end of July 1, 2021. This meta-analysis was performed to evaluate the efficacy of TNT in terms of pathological complete remission (pCR), nCRT or surgical complications, R0 resection, local recurrence, distant metastasis, disease-free survival (DFS) and overall survival (OS) in LARC. RESULTS: Eight nRCTs and 7 RCTs, including 3579 patients were included in the meta-analysis. The rate of pCR was significantly higher in the TNT group than in the nCRT group, (OR 1.85, 95% CI 1.39-2.46, p < 0.0001), DFS (HR 0.80, 95% CI 0.69-0.92, p = 0.001), OS (HR 0.75, 95% CI 0.62-0.89, p = 0.002), nCRT complications (OR 1.05, 95% CI 0.77-1.44, p = 0.75), surgical complications (OR 1.02, 95% CI 0.83-1.26, p = 0.83), local recurrence (OR 1.82, 95% CI 0.95-3.49, p = 0.07), distant metastasis (OR 0.77, 95% CI 0.58-1.03, p = 0.08) did not differ significantly between the TNT and nCRT groups. CONCLUSION: TNT appears to have advantages over standard therapy for LARC in terms of pCR, R0 resection, DFS, and OS, with comparable nCRT and postoperative complications, and no increase in local recurrence and distant metastasis.