Abstract
Smoking is well known as a risk factor for esophageal cancer, but controversial as a prognostic factor. Moreover, evidence is scarce that a dose-response relationship exists. We conducted a retrospective study on the effect and dose-response relationship of prediagnostic smoking on the postoperative disease-specific survival of patients with lymph node-negative esophageal squamous cell carcinoma (ESCC). We enrolled 643 patients with lymph node-negative ESCC who had undergone esophagectomy between 1990 and 2005 at the Department of Thoracic Surgery, Sun Yat-sen University Cancer Center, Guangzhou, China. The patients' demographic, pathological, preoperative and cancer outcome data were obtained from medical records. These data were reviewed and analyzed using life table, Kaplan-Meier analysis and multivariate Cox regression. A significant reduction in 3- and 5-year survival rates was observed in smokers with lymph node-negative ESCC compared with those in non-smokers. The 3- and 5-year survival rates were 54% and 46% for smokers, and 67% and 64% for non-drinkers, respectively (P < 0.05). Multivariate Cox analysis revealed that smoking was an independent prognostic factor (P = 0.008, hazard ratio = 1.404). Both log-rank test (P = 0.065) and multivariate analysis (P = 0.091) showed no significant difference between the survival rates of light and heavy smokers. Prediagnostic smoking is an independent prognostic factor for patients with lymph node-negative ESCC, but the dose-response relationship needs further investigation.