Smoking an Important Risk Factor for Colorectal Polyps

October 22, 2002

Oct. 22, 2002 (Seattle) — Smoking has been identified as an important risk factor for colorectal polyps in a retrospective study conducted by researchers at Stony Brook University in Long Island. Another implication of the study includes a possible departure from standard endoscopic screening guidelines that recommend initial screening begin at age 50 years for those with average cancer risk. Physicians should consider advising patients who smoke to have their first colonoscopy before age 50.

In a panel presentation at the 67th Annual Scientific Meeting of the American College of Gastroenterology here, lead author Rajeev Attam, MD, reported findings that supplement established research identifying family history as a key risk factor for polyps.

The Stony Brook team collected information on three patient groups that had undergone screening colonoscopy from December 1999 through April 2002. The groups consisted of 354 smokers, 364 former smokers, and 848 nonsmokers. Data were also gathered on sex, family, age, prior history of colon cancer, smoking behavior, alcohol consumption, dietary intake of fruits and vegetables, body mass index, weekly exercise, and history of inflammatory bowel disease.

Dr. Attam noted that the proportion of smokers who had more than two polyps was particularly high. Smokers also were much more likely to have polyps larger than 1 cm or have a polyp type with higher future risk for malignancy.

According to Joseph C. Anderson, MD, lead investigator of the study and assistant professor of Medicine at Stony Brook, the study suggests additional implications for colon cancer risk. This is due to the fact that the polyps found in the smokers that were studied were premalignant, or were predictive of future development of cancer after surgical resection.

Dr. Anderson observed that a link between colorectal cancer and polyps is not new information to researchers. Given the absence of randomized controlled prospective studies, however, since scientists cannot promote smoking among potential research subjects, these types of epidemiological studies are very important. "Ours is the first to include major risk factors in a screening study, thus enabling us to measure relative risk factors against each other."

The researchers also concluded that smoking cessation for more than 10 years may reduce the risk of polyps and that consumption of wine, combined with female sex, seems to lower the risk of colorectal polyps.

"Just as the established risk factor of family history is not found in the majority of patients, additional investigations on the role of smoking are required to identify other possible factors at play" in the development of polyps, Karen Woods, MD, FACG, told Medscape. Dr. Woods is a professor of medicine at Baylor College of Medicine in Houston, Texas, and chair of the Educational Affairs Committee of the American College of Gastroenterology.

These additional investigations might include gathering more data on whether the rate of polyp development is faster in smokers, and identifying environmental, dietary, or other as yet undefined risk factors. "More investigations are key since we already know that smoking is associated with lung, head and neck, and pancreatic cancers," Dr. Woods said.

The Stony Brook teams plans to continue collecting data to shed more light on the question of whether or not the onset of polyps is indeed earlier in smokers. At present, a trend has been identified to suggest an affirmative answer, but results are not statistically significant. Patients are still being enrolled in the Stony Brook study on a weekly basis.

From the standpoint of clinical practice, Dr. Anderson believes that a physician's obligation to patients is not just to consider such factors as family history and age, but to advise patients on other risk factors, such as smoking, which would allow them to make important lifestyle and behavioral changes for disease prevention.

67th Annual Meeting of the ACG: Abstract 5. Presented Oct. 21, 2002.

Reviewed by Gary D. Vogin, MD



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