Colorectal cancer is hereditary in more than one-third of younger patients

Among patients diagnosed with colorectal cancer (CRC) at age 35 or younger, 35% had an identifiable hereditary cancer syndrome, according to researchers at the University of Texas MD Anderson Cancer Center in Houston.

In light of this finding, the researchers concluded that patients diagnosed with CRC at age 35 years or younger should receive genetic counseling regardless of their family history and phenotype.

Early-onset CRC is generally defined as a diagnosis before age 50, but the prevalence of CRC in adolescents and young adults is not as well understood. In this study, published in the Journal of Clinical Oncology, investigators reviewed data from 193 patients age 35 and younger who were diagnosed with CRC and underwent genetic counseling at MD Anderson between 2009 and 2013.

Among patients of all ages with CRC, approximately 5% have hereditary cancer syndromes. In the younger age group in this study, the researchers expected a higher proportion of hereditary syndromes, but not as high as what they found. “We were very surprised to find that 35% of that population of patients had a genetic disease,” said study leader Eduardo Vilar-Sanchez, MD, PhD, assistant professor, Clinical Cancer Prevention, at MD Anderson.

Of the 193 patients, 66 had hereditary cancer syndromes—23 had Lynch syndrome, 22 had mutation-negative Lynch syndrome, 16 had familial adenomatous polyposis, 2 had constitutional mismatch repair deficiency, 2 had biallelic MUTYH mutations, and 1 had Li-Fraumeni syndrome.

Patients without a hereditary syndrome more frequently presented with metastatic disease, whereas patients with a syndrome were more likely to present at earlier stages and to have a family history of cancer. Still, about 1 in 5 patients with hereditary syndromes (19%) were patients with no family history of the disease.

“Based on our findings, patients under the age of 35 need to be evaluated by a genetic counselor. Period,” Dr. 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.”