Researcher finds gender differences in smokers' colon cancer risk

The effects of tobacco exposure on colon cancer risk are more immediate in women than in men, according to research by Dr. Joseph C. Anderson.

Anderson, a gastroenterologist in the Colon Cancer Prevention Program at the Health Center’s Carole and Ray Neag Comprehensive Cancer Center, presented his findings at the American College of Gastroenterology’s annual scientific meeting on Oct. 6 in Orlando. He collaborated with former colleague Dr. Zvi Alpern at Stony Brook University in Stony Brook, N.Y.

While Anderson and Alpern’s study associates smoking with a nearly two-fold increase in the risk of developing significant colorectal neoplasia – the formation of tumors in the colon – in both genders, it also finds that it takes less tobacco exposure for women to reach that risk category.

“This sounds yet another warning about the damaging effects of tobacco use, especially for women,” says Anderson.

The researchers collected data from more than 2,700 patients from 1999 to 2006, measuring tobacco use in “pack-years,” the number of packs of cigarettes smoked daily times the number of years spent as a smoker.

Their analysis, controlling for factors such as age, body mass index, and family history, showed that women who smoked up to 30 pack-years had an 82 percent greater risk for significant colorectal neoplasia than nonsmoking women. Men who smoked up to 30 pack-years saw a 21 percent greater risk than nonsmoking men.

“The men do ‘catch up,’ but not until they’ve smoked more than 30 pack-years,” Anderson says.

“Once you get to more than 30 pack-years, male and female smokers both are nearly twice as likely as their nonsmoking counterparts to develop colon cancer. What’s even more alarming about our evidence is, it tells us that women who smoke will reach that danger zone much faster than male smokers will.”