Previous studies have shown that smoking is linked to a two-fold risk for colorectal neoplasia, but less is known about the exposure quantity needed.
For the study, Joseph C. Anderson, M.D., of the University of Connecticut in Farmington and Zvi A. Alpern, M.D. of Stony Brook University in New York compared the quantity of tobacco exposure to increased colorectal cancer risk in men and women.
The levels of tobacco exposure were measured by multiplying the packs of cigarettes smoked per day by the number of years smoked ("pack years.")
In a large cross-sectional study, Anderson and Alpern analyzed data of 2,707 patients (average age 57.3) who underwent colonoscopy between 1999 and 2006.
Data collected included age, height, weight, family history of colon cancer, medication use, surgery, exercise, diet and smoking history.
Patients were divided into three smoking groups: heavy exposure, low exposure, and no exposure. The heavy exposure group was placed into two different groups: those who smoked 30 pack years or less and those who smoked more than 30 pack years.
After taking into account factors such as age, body mass index, and family history, researchers found women who smoked less than 30 pack years were almost twice as likely to develop significant colorectal neoplasia compared to women who were not exposed to cigarette smoke.
"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," said Anderson.
The study has been presented at the 73rd Annual ACG Scientific Meeting in Orlando.