Associations of duration, intensity, and quantity of smoking with adenocarcinoma and squamous cell carcinoma of the esophagus

Smoking has been identified as a risk factor for esophageal cancer; however, there is evidence that magnitudes and patterns of association differ by histologic type. The authors aimed to measure and compare the independent effects of various dimensions of smoking (duration, intensity, total dose, and time since quitting) on risks of esophageal adenocarcinoma (EAC), gastroesophageal junction adenocarcinoma (GEJAC), and esophageal squamous cell carcinoma (ESCC). They used data from a population-based Australian case-control study (2002-2005) comprising 367 EAC cases, 426 GEJAC cases, and 309 ESCC cases and 1,580 controls. Multivariate logistic and generalized additive logistic regression (for nonlinear dose effects) were used. Ever smokers had significantly higher risks of EAC (odds ratio (OR) = 1.7, 95% confidence interval (CI): 1.3, 2.3), GEJAC (OR = 2.4, 95% CI: 1.8, 3.2), and ESCC (OR = 2.8, 95% CI: 2.0, 4.0) than did never smokers; however, there were significant differences in magnitude and patterns of association between subtypes. When multiple dimensions of smoking were assessed concurrently, duration was significantly associated with all three subtypes but intensity was associated only with GEJAC and ESCC, and the associations were nonlinear. For all types of esophageal cancer, time since quitting was independently associated with approximately 15-19% risk reductions per decade.