Efficacy of Neoadjuvant Therapy in Improving Long-Term Survival of Patients with Resectable Rectal Cancer: a Meta-Analysis

Background: The impact of neoadjuvant therapy on long-term prognosis of patients with resectable rectal cancer is currently unknown. Objective: This study aimed to explore the long-term prognosis of patients with resectable rectal cancer following treatment with neoadjuvant therapy. Methods: Four major databases (PubMed, Web of Science, Embase, Cochrane library) were searched to identify relevant articles published between January 2000 and July 2020. The main outcome indicators were the 5-year Overall Survival (OS) and Disease-Free Survival (DFS). Results: The meta-analysis revealed that 5-year OS (HR: 0.88, 95% Cl: 0.83-0.93) and DFS (HR: 0.95, 95% Cl: 0.91- 0.98) were higher in patients with resectable rectal cancer after receiving neoadjuvant therapy than those treated with upfront surgery. Subgroup analysis demonstrated that the long-term survival of patients in Asia and Europe could benefit from neoadjuvant therapy. The neoadjuvant short-course radiotherapy (SCRT) and neoadjuvant chemoradiotherapy (CRT) improved the 5-year OS and DFS of patients with stage II-III rectal cancer and mid/low rectal cancer. Further research found that patients with stage II only had an increase in OS, while patients with stage Ⅲ have improved 5-year OS and DFS. Conclusion: Neoadjuvant therapy improved the long-term survival of patients with mid/low rectal cancer in stage Ⅱ-Ⅲ (especially stage Ⅲ). Additionally, patients in Asia and Europe seemed to be more likely to benefit from neoadjuvant therapy. For the treatment, we recommend neoadjuvant SCRT and neoadjuvant CRT for resectable rectal cancer.