Smoking behavior and smoking index as prognostic indicators for patients with esophageal squamous cell carcinoma who underwent surgery: A large cohort study in Guangzhou, China.

INTRODUCTION This study aimed to evaluate the association between smoking and smoking index with clinical outcomes of esophageal squamous cell carcinoma patients. METHODS This is a retrospective analysis conducted on consecutive patients with esophageal carcinoma who underwent esophagectomy from January 2005 to December 2010. All patients had pathologically confirmed esophageal squamous cell carcinoma. The association between smoking and sociodemographic characteristics with overall survival and disease-free survival was analyzed. Serum carcinoembryonic antigen was measured using an electrochemiluminescence immunoassay. RESULTS A total of 944 patients were enrolled. Kaplan-Meier analysis indicated that esophageal squamous cell carcinoma patients who smoked had a significantly worse prognosis in terms of both overall survival (p=0.007) and disease-free survival (p=0.010). Multivariate analysis demonstrated that age (p=0.001), carcinoembryonic antigen (p=0.012), tumor-node-metastasis (TNM) staging (p<0.001) and smoking (p=0.048) were independently correlated with overall survival, while only TNM stage (p<0.001) and smoking (p=0.041) were identified as independent factors of disease-free survival. We divided the smoking population into two groups (smoking index <400 and =400). Kaplan-Meier survival analysis indicated that a smoking index <400 was associated with a significantly better prognosis in terms of both overall survival (p=0.003) and favorable disease-free survival (p=0.032). Multivariate analysis showed that age (p<0.001), TNM staging (p<0.001), and smoking index (p=0.025) were independent factors of overall survival, whereas for disease-free survival, only TNM stage (p=0.001) and smoking index (p=0.025) were identified. CONCLUSIONS Overall survival was significantly associated with smoking in esophageal squamous cell carcinoma patients. For esophageal squamous cell carcinoma patients who smoke, a higher smoking index is associated with worse clinical outcomes. Therefore, smoking may be used as a predictive indicator for pretreatment evaluation and adjustment of treatment regimen.