Active and passive cigarette smoking and the risk of endometrial cancer in Poland

BackgroundEpidemiological studies have consistently reported that active cigarette smoking is inversely associated with endometrial cancer risk. However, dose-response relationships with quantitative measures of active smoking or passive smoking remain less clear.MethodsData on lifetime active and passive smoking were collected for 551 endometrial cancer cases and 1925 controls in a population-based case-control study conducted during 2001–2003 in Poland (Warsaw and Łódz).ResultsCompared with never active smokers, active current (Odds Ratio (OR) = 0.51, 95% Confidence Interval (CI): 0.39, 0.68) and former smokers (OR = 0.60, 95% CI: 0.45, 0.80) were at a statistically significantly decreased risk. We did not observe statistically significant inverse dose-response relationships with increasing exposure with duration and cumulative measures. However, there was some indication that the highest category of number of years (OR = 0.35, 95% CI: 0.23–0.55), intensity (OR = 0.41, 95% CI: 0.24–0.69), and dose (OR = 0.38, 95% CI: 0.24–0.60) of smoking among current smokers had the greatest inverse association compared to never smokers. Our data did not support the presence of an inverse association with passive smoking among never active smokers (OR = 0.92; 95% CI: 0.65, 1.29).ConclusionOur results support that long-term and heavy smoking among current smokers strongly influence endometrial cancer risk.