Artikel
Cigarette smoking and the risk of colorectal cancer in a German population-based case-control study
Suche in Medline nach
Autoren
Veröffentlicht: | 8. September 2005 |
---|
Gliederung
Text
Introduction
Studies have shown fairly consistent positive relationships between smoking and risk of colorectal adenomas, but studies on smoking and the risk of colorectal cancer have yielded inconsistent results. It has been suggested that a long induction period of smoking is needed for any effect on the risk of colorectal cancer to become apparent.
Materials and methods
We conducted a population-based case-control study in a region of Southern Germany from January 2003 to June 2004. A total of 543 cases with newly diagnosed colorectal cancer and 614 controls matched to cases by sex, 5-year age groups and area of residence were recruited. Subjects were aged 30 and above, and provided information on demographic factors and risk factors of colorectal cancer including lifetime cigarette smoking habits in personal interviews. Odds ratios (OR) and 95% confidence intervals (CI) were computed using conditional logistic regression models adjusting for potential confounders.
Results
The mean ages for the cases and controls were 68.1 (±10.1 standard deviation (SD)) and 66.6 (±10.3 SD) years respectively. Overall, compared with non-smokers there was an increased risk for smoking for 30 years and above (OR: 1.26, 95% CI: 0.91-1.76) and a statistically significant increased risk for more than 30 pack-years of smoking (OR: 1.59, 95% CI: 1.03-2.45). After stratification by sex, the risk estimates were pronounced for females with ORs of 1.98 (95% CI: 1.08-3.63) for smoking for 30 years and above and 3.60 (95% CI: 1.33-9.75) for more than 30 pack-years of smoking. The risk estimates in men were elevated but failed to reach statistical significance. Among smokers, there was evidence of risk reduction after 20 or more years of quitting smoking when compared to current smokers even after adjusting for pack-years of smoking, with a linear trend for risk reduction with time since cessation of smoking (p = 0.07). There were no major differences in the results with respect to sub sites of colon and rectal cancers.
Conclusion
This study supports the hypothesis that smoking for a long duration at a high intensity increases the risk for colorectal cancer and suggests that there might be some risk reduction after quitting smoking in the long run.