Background Smoking increases the risk of esophageal cancer, but its impacts on disease progression, treatment effects, and complications in cancer survivors have rarely been reported.

Objective This study is conducted to explore the influence of smoking history on the clinical outcomes of patients with esophageal squamous cell carcinoma after esophageal stent placement.

Methods From June 2012 to March 2016, patients with esophageal squamous cell carcinoma who underwent ¹²⁵I seed-loaded esophageal stent placement were recruited from five general hospitals in China, and followed up by telephone to September 2016. The patients were grouped according to smoking history (defined as they had ever been a regular cigarette smoker in the past 10 years and smoking ≥ 100 cigarettes in one's lifetime). All those with a smoking history included in this study quit smoking at admission. Their post-operational survival time and complications (defined and diagnosed by clinical standards and methods) were recorded. The stabilized inverse probability of treatment weighting (SIPTW) was used to control selection bias and potential confounding factors in the retrospective study. Chi-square test and Kruskal-Wallis test were used to compare the between-group difference in the occurrence of complications. Multivariate Cox regression models were used to evaluate the post-operational survival in relation to smoking history.

Results Finally a total of 157 patients were included in this analysis, including 91 patients with a history of smoking and 66 patients without. The baseline characteristics were comparable between the two groups after the SIPTW. Compared with the never smokers, except the incidence of total complications (P=0.132), there were significantly higher incidences of pneumonia (15.4% vs. 3.0%, χ²=7.43, P=0.006) and haemorrhage (17.6% vs. 7.6%, χ²=8.79, P=0.002) in the ever smokers. There were 144 (91.7%) patients dead during the follow-up, of which 87 were ever smokers and 57 were never smokers (χ²=4.30, P=0.038). The median (95%CI) survival was 92 (68-319) d for the ever smokers versus 183 (146-195) d for the never smokers (P=0.022). The multivariate Cox regression analysis results showed that smoking history was significantly associated with post-operational survival after esophageal stent placement (HR:1.56, 95% CI:1.03-2.35, P=0.034).

Conclusion Smoking history can increase the post-operational incidence of complications after stent implantation in patients with esophageal squamous cell carcinoma, and is an important risk factor affecting the prognosis of stent implantation. Therefore, patients with a smoking history warrant close clinical attention during palliative care.