More than a third of colorectal cancers diagnosed in younger patients are caused by inherited gene mutations, according to a study published in the Journal of Clinical Oncology.

The research included 193 patients, aged 35 and younger, who were diagnosed with colorectal cancer and underwent genetic testing between 2009 and 2013.

“We were very surprised to find that 35 percent of that population of patients had a genetic disease, although we hypothesized the proportion would be higher in this age group relative to the general population,” study leader Eduardo Vilar-Sanchez, M.D., Ph.D., an assistant professor in the department of clinical cancer prevention at the University of Texas MD Anderson Cancer Center in Houston, said in a cancer center news release.

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“Based on our findings, patients under the age of 35 need to be evaluated by a genetic counselor. Period,” Vilar-Sanchez said. If they find they have a genetic disease, they can then share that information with their parents, siblings, and other family members who could benefit from knowing about the genetic risk, he added.


  1. Mork ME, You N, Ying J, et al. High Prevalence of Hereditary Cancer Syndromes in Adolescents and Young Adults With Colorectal Cancer. Journal of Clinical Oncology. doi: 10.1200/JCO.2015.61.4503. [epub ahead of print]. July 20, 2015.