More than one-third of adolescents and young adults diagnosed with colorectal cancer have hereditary disease, according to a study from The University of Texas MD Anderson Cancer Center.
The study’s findings, which come amid an uptick in the prevalence of colorectal cancer among people younger than 50 years, underscore the need for such patients to be evaluated by a genetic counselor.
The retrospective study, the largest of its kind to date, reviewed data from about 200 colorectal cancer patients age 35 years or younger who received genetic counseling and testing at MD Anderson between 2009 and 2013.
“What we discovered was that more than a third—35%—of the patients had a hereditary colorectal cancer syndrome, which is kind of astounding because previous literature has reported that the frequency of hereditary colorectal cancer in the general colorectal cancer population is only 5%,” said Eduardo Vilar-Sanchez, M.D., Ph.D., an assistant professor in the Department of Clinical Cancer Prevention and the study’s senior author.
Most patients with hereditary colorectal cancer in the study had Lynch syndrome (45 patients) or familial adenomatous polyposis (16 patients). Lynch syndrome conveys a lifetime colorectal cancer risk of up to 80%, and familial adenomatous polyposis in the absence of screening, surveillance, and prophylaxis all but guarantees that colorectal cancer will develop.
“A diagnosis of hereditary cancer has implications for a wider population because that diagnosis extends to the rest of the family,” Dr. Vilar-Sanchez said. “Those family members will need to undergo genetic testing, and if they are diagnosed with a genetic condition, they will need to be doing surveillance and screening.”
Of note, Dr. Vilar-Sanchez said, a substantial proportion of patients with hereditary colorectal cancer in the study were the first in their families to be diagnosed with a hereditary syndrome. In addition, 13 of the patients with hereditary colorectal cancer had germline mutations and no family history of disease. The findings suggest that all patients age 35 years or younger who are diagnosed with colorectal cancer should be referred to receive genetic counseling about hereditary cancer syndromes regardless of their family history.
The study also found that patients with hereditary colorectal cancer were less likely than patients with nonhereditary colorectal cancer to have features indicative of aggressive disease, including left-sided tumors, metastatic disease, poorly differentiated tumors, and tumors with signet ring cells. No such differences were observed among patients with different hereditary syndromes, Dr. Vilar-Sanchez said, noting that the pathological characteristics of tumors from patients with Lynch syndrome were not substantially different than those from patients with familial adenomatous polyposis.
The main takeaway from the study’s findings, Dr. Vilar-Sanchez said, is that there should be a strong suspicion for a hereditary syndrome in patients age 35 years or younger who present with colorectal cancer.
“At some point, most physicians who treat colorectal cancer will probably be caring for a patient who has a hereditary condition, and that requires some extra considerations for their care and has implications for their family members,” Dr. Vilar-Sanchez said.
For more information, contact Dr. Eduardo Vilar-Sanchez at 713-563-4743.
Mork ME, You YN, Ying J, et al. High prevalence of hereditary cancer syndromes in adolescents and young adults with colorectal cancer. J Clin Oncol. 2015;33:3544–3549.
Dineen S, Lynch PM, Rodriguez Bigas MA, et al. A prospective Six Sigma quality improvement trial to optimize universal screening for genetic syndrome among patients with youngonset colorectal cancer. J Natl Compr Canc Netw. 2015;13:865–872.
OncoLog, October 2016, Volume 61, Issue 10