FRIDAY, July 24, 2015 (HealthDay News) -- More than a third of colon cancers diagnosed in younger patients are caused by inherited gene mutations, a new study finds.
These patients should undergo genetic counseling to determine if their families may be at increased risk, the researchers suggested.
Hereditary colon cancers are relatively rare overall, but tend to be more common if diagnosed before age 50, the researchers said. However, their prevalence among teens and young adults has not been well documented, according to the researchers.
This study included almost 200 patients, aged 35 and younger, who were diagnosed with colon 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 Dr. Eduardo Vilar-Sanchez, an assistant professor in the department of clinical cancer prevention at the University of Texas M.D. Anderson Cancer Center, said in a cancer center news release.
The study was published July 20 in the Journal of Clinical Oncology.
"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 said.
Colorectal cancer is the third most common cancer in the United States, with more than 90,000 new diagnoses expected this year, the researchers said. People older than 50 will account for about 90 percent of those cases, they noted.
The American Cancer Society has more about colorectal cancer.