Obese women at greater risk of colorectal cancer

New study findings show a high body mass index (BMI) among women is a more significant risk factor for colorectal neoplasia than for men.

According to data released today at the 69th Annual Scientific Meeting of the American College of Gastroenterology, researchers from Stony Brook University found a positive correlation between increased body mass index (BMI) and the risk of colorectal neoplasia among asymptomatic women who underwent colonoscopies.

The researchers examined a population of 2300 patients, including 1250 men and 1050 women. Overall, their findings reveal that increasing BMI is associated with higher risk of significant colorectal neoplasia. This effect was shown to be statistically significant in women but not men.

The researchers divided the women into several groups based on BMI and evaluated whether their screening tests detected large polyps or multiple polyps, high grade dysplasia (a precancerous change in the colon) or cancer. Women who had a BMI of 40 (considered obese) or more were 5.2 times as likely to have significant colonic neoplasia detected during colonoscopy as women with a BMI of 25 or less (considered healthy weight) while controlling for smoking, age, alcohol use and family history of colorectal cancer.

Explaining the disparity in the findings between men and women, Joseph C. Anderson, M.D., one of the Stony Brook investigators, said, "We use body mass index as a surrogate measure for body fat. It may be that for men and women with similar BMI, women have less muscle than men. This needs to be explored further." According to Dr. Anderson, the implications of this study are important for physicians counseling overweight and obese women about colorectal cancer screening in light of their increased risk.