A new risk score may aid in identifying men and women younger than 50 who are most likely to develop a cancer of the colon or rectum, an international study published by Archaumbault et al in the Journal of the National Cancer Institute showed.
More About Scoring
The score—a number between 0 and 1—is made from a calculation of people’s risk of developing colorectal cancer based on 141 genetic variants more commonly found in people with the disease. This so-called polygenic risk score is then added to a parallel risk calculation based on 16 lifestyle factors known to increase the risk of developing colorectal cancer, including smoking, age, and how much dietary fiber and red meat are being consumed.
Rates of colon and rectal cancers have been on the rise among younger adults in the United States, as well as many other nations. In the United States alone, rates have increased every year from 2011 to 2016 by 2% among people younger than 50.
The new study showed that those with the highest, or top third, combined polygenic and environmental risk scores were four times more likely to develop colorectal cancers than men and women who scored in the bottom third. The study authors wrote, “Based on absolute risks, we can expect 26 excess cases per 10,000 men and 21 per 10,000 women, among those scoring at the 90th percentile for both risk scores.”
“Our study results help address the rising rates of colorectal cancer among younger adults in the United States and other developed countries and show that it is feasible to identify those most at risk of the disease,” said study co–senior investigator Richard Hayes, PhD, DDS, MPH, Professor in the Departments of Population Health and Environmental Medicine at NYU Grossman School of Medicine.
The new study involved a comparison of 3,486 adults under age 50 who developed bowel cancer between 1990 and 2010 with 3,890 similar young men and women without the disease. All were participants in research studies monitoring people for cancer in North America, Europe, Israel, and Australia.
Dr. Hayes cautioned that his team’s tool is not yet ready for clinical use. Before it can be widely adopted, he says further testing is needed in larger trials to refine the model; describe how it can best be used by physicians; and demonstrate that, when used, the scoring system can in fact prevent illness and death.
Dr. Hayes says it remains unclear why the number of colorectal cancers is increasing in younger adults. By contrast, case numbers among older adults have decreased considerably due to advances in screening and increased removal of suspect growths before they advance to cancer.
“Our ultimate goal is to have a predictive test for all people to gauge when they, based on their own genetic and personal health factors, need to start routine screening for colorectal cancer,” said Dr. Hayes.
Disclosure: Support for the study was provided by the National Institutes of Health. For full disclosures of the study authors, visit academic.oup.com.
