Researchers have discovered a high prevalence of hereditary colorectal cancers among those diagnosed before 35, according to a University of Texas MD Anderson Cancer Center news release.
Based on a study published in the Journal of Clinical Oncology, the center is suggesting patients undergo genetic counseling to determine if their families may be at an elevated risk. Researchers defined clinical profiles including the exteny of hereditary cancer syndromes and family history of cancer in patients diagnosed with CRC at age 35 or younger.
About 5% of colorectal cancer cases are caused by hereditary syndromes such as Lynch and familiar adenomatous polyposis. Among patients with early-onset CRC (before age 50) the incidence of hereditary CRC is higher.
Researchers reviewed data from 193 patients with CRC who received genetic counseling at MD Anderson between 2009 and 2013. “We were very surprised to find that 35% of that population of patients had a genetic disease,” Eduardo Vilar-Sanchez, MD, PhD, said in the release. “Although, we hypothesized the proportion would be higher in this age group relative to the general population.”
Of the 35% of patients with genetic disease, 23 had Lynch syndrome, 22 had mutation-negative Lynch syndrome, 16 had familial adenomatous polyposis, two were diagnosed with constitutional mismatch repair deficiency, two with biallelic MUTYH mutations and one with Li-Fraumeni syndrome.
Patients without a hereditary syndrome more frequently presented with metastatic disease while patients with a hereditary syndrome more likely presented at earlier stages and had a family history of cancer.
According to the American Cancer Society, colorectal cancer is the third most common cancer among men and women in the U.S., with more than 90,000 new cases expected this year. About 90% of those cases will be diagnosed in patients over 50. Patients diagnosed with CRC under 35 represent 1.5% of all cases, and therefore face unique challenges related to disease aggressiveness, impact of treatments on fertility and potential genetic risk to family members, Vilar-Sanchez said in the release.
Genetic testing in family members will identify those with high-risk mutations and allow them to take proper preventive actions, such as behavioral modification to reduce other environmental risk factors, according to the release. There’s also the potential for them to participate in earlier screening, increased surveillance, prophylactic surgeries and chemoprevention studies, Vilar-Sanchez said.
“Based on our findings, patients under the age of 35 need to be evaluated by a genetic counselor. Period,” Vilar-Sanchez said. “The translation of that information extends well beyond the patient as there are tremendous benefits from being able to share genetic risk with their parents, siblings and many other family members.”
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