Prognostic impact of cigarette smoking on the survival of patients with established esophageal squamous cell carcinoma receiving radiotherapy: A retrospective study from southern China

Cigarette smoking is associated with the development of esophageal squamous cell carcinoma (ESCC); however, the influence of smoking on survival of patients with ESCC receiving radiotherapy, with or without chemotherapy, has remained elusive. The present study retrospectively analyzed 479 patients with ESCC from southern China who were categorized based on their smoking history (never, previous or current). To consider the cumulative effect of smoking, the number of pack years (PYs) was used as a representative variable. Associations between cigarette smoking and survival were evaluated using the Kaplan-Meier analysis and Cox proportional hazards model. Among the 497 patients, 308 (64.3%) had reported a history of cigarette smoking. The 5-year overall survival for patients void of a smoking history, former smokers and current smokers was 50.9, 27.0 and 34.3%, respectively. The adjusted hazard ratios (HRs) for previous and current smoking vs. no smoking history were 1.57 [95% confidence interval (CI), 1.06-2.32] and 3.01 (95% CI, 1.15-7.86), respectively. Heavy smokers with a high number of PYs had a HR for death of 1.75 (95% CI, 1.28-2.41) compared with light smokers. In the cohort of 407 patients treated with intensity-modulated radiotherapy/three-dimensional conformal radiotherapy, similarly significant results were obtained. In conclusion, cigarette smoking is an independent and poor prognostic factor for patients with ESCC treated with radiotherapy and/or chemotherapy. It is associated with an increased risk of death, and the risk increases with the increase in PYs. This result may help to manage tobacco use among patients with ESCC. The smoking status should be taken into consideration in prospective studies on ESCC. More frequent follow-ups are recommended for those patients with ESCC with a history of smoking.