Study Links Smoking to Colorectal Cancer

Lung, mouth, and bladder cancers, among others, are well established as cancers caused by cigarette smoking. A recent study from the American Cancer Society, published in the Journal of the National Cancer Institute shows that cigarette smoking also raises the risk of dying from colorectal cancer, which is cancer of the colon or rectum. Indeed, the study notes that as many as 12% of colorectal cancer deaths in the United States may be associated with smoking.

Researchers analyzed data from 312,332 men and 469,019 women enrolled in the Cancer Prevention Study II. They found that for both men and women, risk of colorectal cancer increased after 20 or more years of smoking. Among men, current smokers were 31% more likely to die from colorectal cancer than nonsmokers; female smokers were 41% more likely than nonsmokers to die from the disease. The risk of death from colorectal cancer rose with the number of years cigarettes were smoked, the number of cigarettes smoked per day, and the number of packs smoked over the years. In addition, the risk of death was higher the younger a person was when he or she started smoking. The association was not confined to cigarette smoke. Those who smoked pipes or cigars also faced a significantly increased risk of death from colorectal cancer.

The bright spot of the study was that it showed a benefit from quitting. Twenty years after quitting, men's risk of colorectal cancer death returned to normal. And women who had stopped smoking 10 or more years earlier had the same risk as nonsmokers. The take-home message: If you smoke, stop. If you don't smoke, don't start.