STUDY: Risk low in under 50 age group.

JOURNAL: The New England Journal of Medicine 2002;346:1781-1785

AUTHORS: Dr. Thomas F. Imperiale

ABSTRACT: The number of healthy people without other risk factors who are likely to develop colon cancer before the age of 50 is relatively low compared with older people, new study findings indicate.

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COMMENTARY: The findings confirm that one of the current colon cancer screening guidelines--a colonoscopy starting at age 50--is still an appropriate recommendation, according to the researchers.

In colonoscopy, a flexible, lighted tube is used to examine the entire colon for polyps, which can become cancerous. Most average risk patients are advised to undergo colonoscopy every 10 years starting at age 50. Higher-risk patients, including those with a family or personal history of colorectal cancer, are advised to get a colonoscopy more frequently or starting at a younger age.

In the current study, lead author Dr. Thomas F. Imperiale of Indiana University School of Medicine in Indianapolis and colleagues evaluated colonoscopy data for 906 men and women aged 40 to 49 years. None of them had symptoms or a family history of colorectal cancer, according to the report in The New England Journal of Medicine.

Overall, 21% had polyps or other suspicious looking lesions or growths, but none were found to have actual cancer, the authors report. Some of the lesions were located in areas where they could be picked up by a sigmoidoscope, an instrument used to examine the lower part of colon.

Based on the their findings, Imperiale and colleagues write that "if these results are applicable to the general population, at least 250 persons, perhaps 1,000 or more, would need to be screened to detect one cancer in this age group."

The researchers suggest that even though 7% of colorectal cancer cases occur in people under 50, the absolute risk of developing cancer is relatively low in that age group. The incidence of colorectal cancer in those aged 45 to 49 years is 24 cases per 100,000 people, while this jumps to 48 per 100,000 in those aged 50 to 54, according to the report.

"Our findings support the observation that age is a good predictor of risk," said Imperiale in a prepared statement.

In other words, the low risk of colon cancer in people in their 40s doesn't appear to warrant recommending everyone in this age group to get a colonoscopy.



Nonetheless, men and women, regardless of their age, who think they may be at risk or have symptoms such as rectal bleeding speak with their physician about the need for screening or for a diagnostic evaluation.