Add Cancer of Colon and Rectum to List of Cigarette Crimes
The study follows on the heels of a report in the Nov.15 issue of the same journal that suggested a possible explanation for how cigarette smoking could cause some cases of cancer of the colon and rectum. Authors of that study found that cigarette smoking might in some people interfere with a gene that directs cells to repair themselves when they are damaged. Together, the two reports put another nail in the coffin of "coffin nails," says Marty Slattery, PhD, author of the second study.
"What our study does is to add support to their finding, that there is a mechanism whereby cigarettes can actually cause alterations in the tumors themselves," Slattery, professor of family and preventive medicine at the University of Utah School of Medicine in Salt Lake City, tells WebMD.
Chao and colleagues looked for a possible link between cigarette smoking and colorectal cancers among nearly 800,000 men and women who were among the participants in the Cancer Prevention Study II, a nationwide study of cancer deaths begun by the ACS in 1982.
"These [data] are adjusted for a number of other factors, because colorectal cancer has multiple factors related to the cause of it," Chao tells WebMD. "We tried to adjust for a number of them, including education, family history, exercise, whether they use aspirin or multivitamins, whether they drink alcohol, intake of foods like vegetables, grains, and fatty meats, and also estrogen replacement therapy. After adjustment, the estimates that we observed with smoking didn't go away, and in fact in former-smoking women it became stronger."
Although the association between smoking and colorectal cancer is not nearly as strong as that between smoking and lung cancer, there is evidence that cancer-causing substances in tobacco damage the lining of the colon and that the risk may be greater among people with a genetic predisposition to colorectal cancer, the authors say.