Neoadjuvant chemotherapy versus neoadjuvant chemoradiotherapy for cancer of the esophagus or the gastroesophageal junction: A meta-analysis based on clinical trials

Background The benefit of neoadjuvant chemotherapy and neoadjuvant chemoradiotherapy for treating cancer of the esophagus or the gastroesophageal junction remains controversial. In the present study, we conducted a comprehensive meta-analysis to examine the efficacy of these two management strategies. Methods The MEDLINE (PubMed), SinoMed, Embase, and Cochrane Library databases were searched for eligible studies. We searched for the most relevant studies published until the end of September 2017. Data were extracted independently and were analyzed using RevMan statistical software version 5.3 (Cochrane Collaboration, http://tech.cochrane.org/revman/download). Weighted mean differences, risk ratios (RRs), and 95% confidence intervals (Cls) were calculated. Cochrane Collaboration's risk of bias tool was used to assess the risk of bias. In this comprehensive meta-analysis, we examined the efficiency of neoadjuvant chemotherapy and neoadjuvant chemoradiotherapy for the treatment of cancer of the esophagus or the gastroesophageal junction as reported in qualified clinical trials. Results Six qualified articles that included a total of 866 patients were identified. The meta-analysis showed that for 3-year and 5-year survival rates in primary outcomes, the results favored neoadjuvant chemoradiotherapy strategies compared with neoadjuvant chemotherapy (RR = 0.78, 95% CI = 0.62-0.98, P = 0.03; RR = 0.69, 95% CI = 0.50-0.96, P = 0.03, respectively). In terms of secondary outcomes, neoadjuvant chemoradiotherapy significantly increased the rate of R0 resection and pathological complete response as well (RR = 0.87, 95% CI = 0.81-0.92, P < 0.0001; RR = 0.16, 95% CI = 0.09-0.28, P < 00001, respectively). However, there were no significant differences in postoperative mortality between the two groups (RR = 1.85, 95% CI = 0.93-3.65, P = 0.08). For the results of postoperative complications, revealed that there was a statistically significant difference between the two groups in the incidence of postoperative complications such as pulmonary, anastomotic leak and cardiovascular complications. The subgroup analysis of patients with esophageal adenocarcinoma or squamous cell carcinoma showed that both esophageal adenocarcinoma and squamous cell carcinoma patients achieved a high rate of R0 resection (RR = 0.85, 95% CI = 0.77-0.93, P = 0.0006; RR = 0.88, 95% CI = 0.81-0.96, P = 0.005, respectively) and pathological complete response benefit of neoadjuvant chemoradiotherapy (RR = 0.23, 95% CI = 0.09-0.57, P = 0.001; RR = 0.18, 95% CI = 0.03-0.96, P = 0.05, respectively). Conclusion Our findings suggested that compared with neoadjuvant chemotherapy, neoadjuvant chemoradiotherapy should be recommended with a significant long-term survival benefit in patients with cancer of the esophagus or the gastroesophageal junction. In view of the clinical heterogeneity, whether these conclusions are broadly applicable should be further determined.