Cigarette smoking may be a risk factor for rectal — but not colon — cancer. The evidence linking cigarette smoking and colorectal cancer risk has been inconsistent.
After an average follow-up of about 8 years, 1,242 women were diagnosed with colorectal cancer. Increased colorectal cancer incidence was associated with more cigarettes smoked per day, more years as a smoker, and older age when the women quit smoking.Current smokers were at an increased risk for rectal cancer, but not colon cancer, compared with never smokers. Secondhand exposure to cigarette smoke was not associated with either cancer.
Journal of the National Cancer Institute. “Smoking is Associated with Rectal Cancer.” ScienceDaily. ScienceDaily, 14 November 2007.