"Alcohol is pernicious with regard to colorectal" tumours, Dr Joseph C Anderson from Stony Brook University, New York said. "Lifestyle plays a role as genetics does in the development" of these tumours.

Anderson and associates investigated the impact of regular alcohol consumption on colorectal tumours in 2291 patients undergoing screening colonoscopy.

Patients defined as heavy beer or spirits drinkers had more than twice the risk of developing significant colorectal tumours, compared with abstainers or moderate consumers, the authors reported.

Moderate wine drinkers, on the other hand, faced about half the risk experienced by abstainers.

Anderson added that he and his colleagues were currently comparing the effects of red and white wine.

Red wine, "due to high levels of (the natural antioxidant resveratrol", should be even more protective against colorectal tumours than white wine, he said.

Colorectal tumours were also associated with smoking, obesity and age, with those older than 60 more susceptible, the report indicated.

The investigators noted that "patients who regularly drink spirits have an increased risk for significant colorectal [tumours] and perhaps should be targeted for risk modification by their gastroenterologist in addition to their primary care physician".

In fact, Anderson noted: "I would target anyone who has more than one beer or drink per day."