People who smoke may face a higher-than-average risk of developing bowel cancer, new research suggests.
Scientists found that people who had smoked for over 40 years or who did not quit before the age of 40 were between 30 and 50 per cent more likely to develop bowel or rectal cancer during the study period.
The researchers followed almost 185,000 people aged 50 to 74 years from 1992 to 2005 in order to make their observations, which are published in the journal Cancer Epidemiology, Biomarkers & Prevention.
The link between smoking and bowel cancer was apparent, even after alcohol consumption, lack of exercise and consumption of red and processed meat had been taken into account.
Senior author Dr Michael Thun, from the American Cancer Society, commented: "This provides one more reason not to smoke, or to quit as soon as possible.
"Colorectal cancer should be added to the list of cancers caused by smoking."
While smoking is usually associated with lung cancer, it also raises the risk of several other forms of the disease, including cancers of the mouth, voice box, oesophagus, liver, pancreas and stomach.