Using Risks To Tailor Screening for Colorectal Cancer. Ann Intern Med. 2003;139:I-10. doi: 10.7326/0003-4819-139-12-200312160-00001
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Published: Ann Intern Med. 2003;139(12):I-10.
Cancer of the colon or rectum is called colorectal cancer. It is the second leading cause of death from cancer in the United States. Polyps (outgrowths of the wall of the colon) precede most colorectal cancers. Screening procedures can detect and remove polyps before they become cancers and also detect early cancers that may be cured with surgery. For example, doctors can use a short flexible tube to look for polyps in the lower half of the colon (sigmoidoscopy) or a longer tube to look at the entire colon (colonoscopy). They can take tissue samples (biopsies) and remove polyps with either procedure. Many doctors use sigmoidoscopy to screen for polyps and/or cancer. If this exam finds polyps, they then do colonoscopy to check for more polyps in the upper part of the colon. Methods that identify people with low risk for polyps in the upper colon might help doctors and patients decide when sigmoidoscopy alone is enough.
To find a way of identifying people with low risks for colorectal cancer in the upper colon for whom sigmoidoscopy screening might be sufficient.
3025 adults age 50 years and older who participated in a company-based screening program. None had symptoms of colorectal cancer.
Participants were screened with colonoscopy. The location and size of any polyps that were found were noted before their removal. Pathologists examined removed tissue to identify advanced growths (precancerous polyps or cancer). The researchers first looked at data from the 1994 people who were screened between September 1995 and December 1998. They identified factors that were associated with an increased probability of finding advanced growths in the upper part of the colon. They developed a risk index that scored and summed those factors. They then tested how well the risk index worked using data from 1031 people who were screened between January 1999 and June 2001.
In people examined between 1995 and 1998, the researchers found that three factors increased the probability of finding advanced growths in the upper part of the colon. These factors were older age, male sex, and certain types and sizes of polyps in the lower part of the colon. Using these factors, the researchers scored risk for advanced growths in the upper colon as low (0 to 1 point), intermediate (2 to 3 points), and high (4 to 7 points). The risk index worked in the second group of people examined between 1999 and 2001. Advanced growths in the upper part of the colon were found in 0.4%, 1.9%, and 3.8% of those classified as low, intermediate, and high risk, respectively.
The risk index was derived in people who had the location of polyps assessed at colonoscopy rather than from people who had polyps in the lower colon detected at sigmoidoscopy. The index needs testing in additional populations.
A risk index may identify low-risk people whose probability of advanced growth in the upper colon is about 1 in 250 (0.4%). The index may help identify people who don't need colonoscopy after sigmoidoscopy.
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Gastroenterology/Hepatology, Hematology/Oncology, Cancer Screening/Prevention, Gastrointestinal Cancer, Colorectal Cancer.
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