All relatives of individuals with colorectal cancer are at increased risk for this cancer, regardless of the age of diagnosis of the index patient in the family, according to a study published online in Clinical Gastroenterology and Hepatology, the official clinical practice journal of the American Gastroenterological Association. These findings may impact future guidance regarding colorectal cancer screening.
"Most surprising, we identified a more than two-fold increase in risk of colorectal cancer among young first-degree relatives (under 50 years of age) of individuals diagnosed with colorectal cancer at advanced ages (60 to 80 years)," said lead study author N. Jewel Samadder, MSc, MD, from Huntsman Cancer Institute at the University of Utah. "This risk is not currently appreciated. Increased awareness of this risk may serve as incentive to increase screening intensity for all patients with a first-degree family history of colorectal cancer."
The researchers conducted a population-based case-control study in Utah identifying 18,208 index patients from the Utah Cancer Registry diagnosed with colorectal cancer between 1980 and 2010; age- and sex-matched cancer-free individuals were selected to form the comparison group. Increased risk was observed in all relatives regardless of age of the family member's cancer diagnosis, although the risk was greatest for young relatives (under 50 years) of individuals who were diagnosed with colorectal cancer before 40 years of age. However, familial risk was increased in first-degree relatives even when the index case was diagnosed with cancer at an advanced age (older than 80 years).
These findings support the current screening guidelines for patients with a family history of colorectal cancer, primarily more aggressive screening for first-degree relatives of persons with colorectal cancer at an age younger than 60 years. However, because colorectal cancer diagnosis even in an older patient can be a predictor of higher risk of this cancer in their relatives, relatives might benefit from knowing this moderate risk and thus avoiding known modifiable risk factors and consider preventative measures.
Colorectal cancer is the fourth most common cancer in the U.S. and is the second leading cause of cancer-related mortality. Heritability is one of the strongest risk factors for colorectal cancer.
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