Smoking and the association of advanced colorectal neoplasia in an asymptomatic average risk population: analysis of exposure and anatomical location in men and women.

Background: Identifying risk factors for advanced colorectal adenomas may aid in colorectal cancer (CRC) screening, especially in light of the American College of Gastroenterology's recent guidelines, emphasizing cancer prevention through identification and removal of advanced adenomas. Smoking is an important risk factor for advanced adenomas but there is little data regarding levels of exposure for genders.

Methods: The aim of this study was to use an existing database to examine the genders separately with respect to exposure level and anatomic location of advanced adenomas. Our database was designed to study smoking in an asymptomatic, screening population. Data included demographics, family history of CRC, smoking exposure (pack-years and years smoked), alcohol, diabetes, medications, exercise and dietary history. We excluded patients with a first degree relative with CRC.

Results: Compared to non-smokers, female smokers had an increased risk for advanced adenomas with an exposure of 10-30 pack-years (adjusted odds ratio [AOR] = 4.11; 95% confidence interval [CI], 1.88-9.01) as well as for ≥30 pack-years (AOR = 2.54; 95% CI, 1.08-5.96) while men had an increased risk with smoking ≥30 pack-years (AOR = 3.10; 95% CI, 1.71-5.65). An increased association with smoking was observed for proximal advanced adenomas (AOR = 4.06; 95% CI, 1.62-10.19) and large hyperplastic polyps in women.

Conclusions: Women smokers had an increased risk for advanced adenomas at a lower exposure level and had a greater risk for proximal lesions. These findings may have an impact on CRC screening for women.