Exposure to Cigarette Smoke Increases Risk of Colorectal Cancer

In that numerous studies have reported a 20% to 60% increase in risk of colorectal cancer associated with active smoking, Michael J. Thun, from the American Cancer Society (Georgia, USA), and colleagues followed 184,187 people for a thirteen-year period, to examine the relationship of cigarette smoking to incident colorectal cancer.  The researchers found that current smokers have a 27% increased risk of colorectal cancer and former smokers a 23% increased risk.  Additionally, the team found that those subjects who smoked for at least half a century were at the highest risk -- 38% higher than never smokers.  No increased risk was found among those who quit smoking before the age of 40, or who had not smoked for 31 or more years.