As reported by the New Haven Register, October 8, 2008.

Study: Smoking Increases Colorectal Cancer Risk

By Abram Katz

Women who smoke fewer cigarettes than men still face the same two-fold increase in the risk of colorectal cancer, according to a study conducted at the University of Connecticut Health Center.

While family history, obesity and age have been considered primary risk factors for colorectal cancer, smoking largely has been overlooked by researchers and journals, said Dr. Joseph C. Anderson, associate professor of medicine at the UConn Health Center and one of the principal investigators in the study.

The basic lifetime risk for colon cancer in the U.S. is about 5 percent, or 1 in 20. A two-fold increase would be 10 percent, or 1 in 10. Findings suggest smokers should be screened more frequently for colon cancer than nonsmokers.

Results were delivered in a talk during a prestigious plenary session of the American College of Gastroenterology Monday in Orlando, Fla.

“Smoking is a definite risk for colon cancer and people have ignored it,” Anderson said Tuesday.

Carcinogenic chemicals in cigarette smoke are transported to the large intestine in saliva, Anderson said. Exposure of the chemicals to the colon wall trigger cell changes that result in cancerous polyps, he said.

Not counting skin cancer, colorectal cancer is the third most common malignancy found in men and women in the U.S., according to the American Cancer Society. The ACS estimates there are about 108,070 new cases of colon cancer and 40,740 new cases of rectal cancer in the United States annually. Combined, they cause about 49,960 deaths.

Using data from about 2,700 colonoscopy patients from 1999 to 2006, Anderson and Dr. Zvi A. Alpern of Stony Brook University in New York compared the incidence of colon cancer and history of smoking.

Data collected included age, height, weight, family history of colon cancer, medication use, surgery, exercise, diet, and smoking history.

Researchers measured smoking in “pack years.” Thus, someone who smoked two packs a day for 15 years was equivalent to another patient who smoked 1 pack a day for 30 years.

Researchers found that women who smoked less than 30 pack years were almost twice as likely to develop significant colorectal cancer compared to female nonsmokers.

“While men and women shared a similar two-fold risk for developing significant colorectal neoplasia, women required less tobacco exposure in pack years than men to have an increase in colorectal cancer risk,” Anderson said.

Women who smoked up to 30 pack years had an 82 percent greater risk of colorectal cancer than non-smoking women, while men who smoked the same amount faced a 21 percent higher risk than non-smoking men.

Men’s risk doesn’t catch up until they smoke more than 30 pack years.