Increasing the interval between neoadjuvant chemoradiotherapy and surgery in esophageal cancer: a meta-analysis of published studies

The aim of this meta-analysis was to clarify whether a longer interval between the end of neoadjuvant chemoradiotherapy (nCRT) and surgery is associated with better outcomes in esophageal cancer. nCRT followed by surgery is the most common approach for patients with resectable esophageal cancer. Operations are performed within 2-8 weeks after nCRT; however, the optimal interval between nCRT and surgery for esophageal cancer is unknown. We performed a systematic literature search in MEDLINE, EMBASE, the Cochrane Central Register of Controlled Trials, and the Clinical Trials database for studies published between January 2000 and December 2014. Eligible studies were prospective or retrospective studies of esophageal cancer that assessed the effects of intervals longer or shorter than 7-8 weeks between the end of nCRT and surgery. The primary end-points were the overall survival (OS) and pathologic complete response (pCR). Secondary end-points were anastomotic leak, R0 resection, and postoperative mortality rate. A meta-analysis was performed to estimate odds ratios (ORs) using fixed-effect and random-effect models, with Review Manager 5.2. The five studies that met the eligibility requirements included 1,016 patients: 520 in the shorter interval group (<= 7-8 weeks) and 496 in the longer interval group (> 7-8 weeks). The results of our meta-analysis indicate that a longer interval between nCRT and surgery may be disadvantageous for 2-year OS (OR = 1.40, 95% confidence interval [CI]: 1.09-1.80, P = 0.010) and R0 resection rate (OR = 1.71, 95% CI: 1.14-2.22, P = 0.009). The pCR, anastomotic leak rate, and postoperative morbidity were similar in the two groups. A longer interval (more than the standard 7-8 weeks) from the end of preoperative nCRT to surgery did not increase the rate of pCR in esophageal cancer, and the different intervals had similar effects on anastomotic leak rate and postoperative mortality rates. However, the longer interval between nCRT and surgery may be disadvantageous for long-term OS. These results should be validated prospectively in a randomized trial.