Colorectal Cancer in Distant Family Can Increase Risk

Positive second- and third-degree family history can affect CRC risk, though less than first-degree

MONDAY, March 29 (HealthDay News) -- Having a family history of colorectal cancer (CRC) in second- and third-degree relatives can increase an individual's risk of the disease when combined with a first-degree family history, according to research published in the March issue of Gastroenterology.

David P. Taylor, of the University of Utah in Salt Lake City, and colleagues analyzed data from the Utah Population Database on more than 2.3 million individuals who were included in family histories of at least three generations. More than 10,000 had a diagnosis of CRC.

The researchers found that the familial relative risk in people with at least one affected first-degree relative was 2.05. In those without a first-degree family history, but with one affected second-degree and two affected third-degree relatives, the familial relative risk was 1.33. Probands with one affected first-degree, one affected second-degree, and at least three affected third-degree relatives had a familial relative risk of 3.28.

"In summary, this study is unique in providing definitions of CRC risk based on first-, second-, and third-degree family history constellations that have not been reported previously," the authors conclude. "We have demonstrated that, although influencing risk to a lesser extent than first-degree family history, positive second- and third-degree family histories can have a significant effect on a person's risk of CRC."

A co-author is a consultant for Myriad Genetics.

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