CHICAGO --- Alcohol use, tobacco smoking and male gender are associated with an earlier onset of colorectal cancer and also with location of tumors, according to a study by Northwestern University researchers.
Findings from the study, published in the March 27 issue of the Archives of Internal Medicine, suggest that individuals who smoke and drink should undergo screening for colorectal cancer earlier in adulthood than at 50 years, the age currently recommended by the National Institutes of Health.
Hemant K. Roy, M.D., associate professor of medicine at Northwestern University Feinberg School of Medicine, and colleagues at Evanston-Northwestern Healthcare examined the records of 161,170 patients with colorectal cancer to assess whether certain risk factors -- alcohol and tobacco use -- should be considered in screening decisions.
Patients who were classified as alcohol or tobacco users, defined as those who smoked or drank alcohol in the previous year, developed cancer at a younger age than non-drinkers and non-smokers. Current alcohol and tobacco users developed cancer an average of almost eight years earlier (age 63 years in women and 62 years in men) than those who never drank or smoked.
Those who never smoked but drank or who never drank but smoked were each an average of five years younger at cancer diagnosis than those who neither smoked nor drank. Individuals who stopped drinking one year or more prior to the study and never smoked developed cancer an average of two years earlier than those who never drank or smoked.
The effect of smoking appeared to be particularly strong for women: Women who smoked but never drank developed cancer six years earlier than those who never drank or smoked, compared with almost four years in men.
The researchers also found that current alcohol and tobacco consumption was associated with an increased likelihood of distal (lower portion of large intestine) colorectal cancer, although women in all categories were less likely to have distal cancer than men.
Distal tumors, including those in the lower left part of the colon and the rectum, can generally be detected by flexible sigmoidoscopy, while proximal (upper part of large intestine) tumors in the right side of the colon can be missed by methods other than colonoscopy.
Flexible sigmoidoscopy involves inserting a flexible optical instrument through the rectum into the lower portion of the large intestine. Colonoscopy, which involves inserting a longer flexible optical instrument through the rectum and into the upper portion of the large intestine, is more expensive, has higher complication rates and usually is performed by a gastroenterologist or surgeon rather than a primary care physician.
The authors suggested that women who do not smoke or drink may be more prone to proximal cancers and might therefore want to consider undergoing colonoscopy instead of flexible sigmoidoscopy.
“In the future, we envision the development of risk scores with non-hereditary (e.g., alcohol and tobacco use, age, body mass index, diet and calcium consumption) and hereditary factors to tailor an individual’s colorectal screen program,” the authors concluded.
Anna L. Zisman, M.D., a resident physician at Evanston-Northwestern Healthcare, was first author on the article.
This research was supported in part by a grant from the National Institutes of Health.