People with colon cancer who smoked and drank alcohol appeared to develop the disease up to a decade earlier in life than those without the habits, a study has shown, suggesting that some people should be screened for the disease much earlier than currently recommended.
Under North American guidelines, people with no family history of colorectal cancer are advised to start testing for precancerous intestinal polyps at age 50. Those with a close relative affected by the disease would begin regular testing earlier.
But a U.S. study of more than 160,000 people with colon cancer suggests that age 50 may be too late for those who smoke tobacco and/or use alcohol to begin screening, which often includes a colonoscopy to view inside the large intestine.
"What we found was not only was the age of onset [of cancer] earlier, but it was actually significantly earlier, in some close to a decade," said principal researcher Hemant Roy, a gastroenterologist at Northwestern University.
Men tended to develop colorectal cancer at an earlier age than women, whether or not they smoked or drank alcohol, Dr. Roy said yesterday from Evanston, Ill. "But the effect of tobacco and alcohol was equally great in women and men."
The study, which analyzed data from a registry of colorectal cancer patients between 1993 and 2003, found that alcohol and tobacco users were diagnosed with the disease 7.8 years earlier on average (age 63 in women and 62 in men) than those who never drank or smoked.
Non-smokers who drank and non-drinkers who smoked were on average 5.2 years younger at cancer diagnosis than those who neither smoked nor drank, the study showed.
"When you put those two together [smoking and drinking], you got kind of an added effect," he said.
Smoking appeared to affect women in particular: women who smoke but never drank developed cancer 6.3 years earlier than those who never drank or smoked, compared with 3.7 years for men.
Dr. Roy said the study has limitations because the data did not include how much patients drank or smoked or for how long. Genetic predisposition because of a family member with the disease was also not captured in the data.
