Diabetes mellitus and survival of esophageal cancer patients after esophagectomy: a systematic review and meta-analysis.

Diabetes mellitus (DM) is one of the most common comorbidities in esophageal cancer patients who undergo esophagectomy. It is well established that DM has an unfavorable impact on short-term outcomes of patients with surgically treated esophageal cancer; however, whether DM has any impact on long-term survival of these patients remains unclear. We performed the first meta-analysis to investigate the impact of DM on survival of surgically treated esophageal cancer patients. We searched the following databases systematically to retrieve relevant studies on January 2, 2019: PubMed, Embase, and Web of Science. The main outcome data consisting of 3- and 5-year overall survival (OS) rates and hazard ratios (HRs) of OS were extracted to compare survival between patients with and without DM. We finally included for meta-analysis a total of eight cohort studies involving 5,044 esophageal cancer patients who underwent esophagectomy. We found no significant difference between 3-year (risk ratio [RR] = 0.94, 95% CI: 0.73-1.21; P = 0.65) and 5-year (RR = 0.92, 95% CI: 0.80-1.08; P = 0.31) OS rates between patients with and without DM after esophagectomy. Moreover, DM was not found to be an independent predictor of OS for these patients (HR = 1.10, 95% CI: 0.65-1.84; P = 0.72). Our study suggests that DM appears to have no significant impact on long-term survival of esophageal cancer patients who undergo esophagectomy. To improve the prognosis of these patients, it may be more important to control glycemic level in patients with DM who undergo esophagectomy. However, further high-quality studies with appropriate adjustment for confounding factors are needed to verify this conclusion.