Can the addition of radiotherapy postoperatively increase clinical outcome of patients with gastric cancer? A systematic review of the literature and meta-analysis

BACKGROUND: Although several studies have been carried out to determine the best treatment for gastric carcinoma, the data on survival rate still remain inconclusive. OBJECTIVE: To evaluate the effects of postoperative radio-chemotherapy on overall and disease-free survival. DATA SOURCES: MEDLINE and CANCERLIT searches of reference lists (for the period 1970 to 2016) were supplemented with hand search of reference lists. STUDY SELECTION: The present work includes randomized controlled trials comparing postoperative radio-chemotherapy to postoperative chemotherapy or to surgery alone in patients with resected gastric carcinoma without evidence of metastatic disease. Ten randomized controlled trials were analyzed in total: four compared postoperative radiochemotherapy to surgery alone (708 patients), and six compared postoperative radiochemotherapy to postoperative chemotherapy (1020 patients). DATA EXTRACTION: According to “intention to treat” method, three independent observers have extracted from each trial, the data on patients, intervention, and outcomes. These data were subsequently combined using DerSimonian and Laird methods. RESULTS: Postoperative radiochemotherapy significantly increases 3-year and 5-year overall survival and 3-year and 5-year disease free survival rate compared to postoperative chemotherapy (RR 0.89; 95%CI 0.81-0.97 and RR 0.82; 95%CI 0.71–0.95) or surgery alone (RR 0.83; 95% CI 0.77-0.91 and RR 0.80; 95% CI 0.65–0.98). CONCLUSIONS: In patients with resected gastric cancer, postoperative radiochemotherapy obtains: 1) an increase in overall survival, 2) an increase in disease free survival, and 3) a gain in 5 year disease free survival independent of surgical procedure.