People who smoke face greater risk of developing precancerous polyps called flat adenomas in the large intestine, a new study available?in Los Angeles?on Saturday suggests.

The finding may explain the earlier onset of colorectal cancer among smokers, said study researchers at the University of Connecticut Health Center.

To determine the link between smoking and the risk for developing the flat polyps, the research team followed 600 patients, at average age 56, who underwent a colonoscopy screening without previously displaying any symptoms for colorectal cancer.

Patients were asked to provide a wide range of demographic information, including smoking history. A little more than half were deemed nonsmokers, while 115 were considered heavy smokers and 172 were considered light smokers.

In addition to being older and male, being a heavy smoker was linked to having flat adenomas of any size, the researchers found. Heavy smoking was also found to be linked to having advanced-stage flat polyps.

The authors concluded that smoking is a strong risk factor for developing flat colorectal adenomas in general, and for having particularly large adenomas.

Flat adenomas are more aggressive and harder to spot than the raised polyps that are typically detectable during standard colorectal screenings, according to the study appearing in the June issue of Gastrointestinal Endoscopy.

This fact, coupled with their association with smoking, could also explain why colorectal cancer is usually caught at a more advanced stage and at a younger age among smokers than nonsmokers, the study said.

"Little is known regarding the risk factors for these flat lesions, which may account for over one-half of all adenomas detected with a high-definition colonoscope," study author Dr. Joseph C. Anderson said in a news release from the American Society for Gastrointestinal Endoscopy.

But, "smoking has been shown to be an important risk factor for colorectal neoplasia (tumor formation) in several screening studies," he said.