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Colorectal cancer in adolescents, young adults more likely to have had heredity predisposition
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The prevalence of hereditary cancer syndromes appeared higher in patients diagnosed with colorectal cancer before the age of 35 years compared with the general population of patients with colorectal cancer, according to study results.
About 2% to 5% of all colorectal cancer cases are considered hereditary and caused by germline mutations; however, the incidence of hereditary syndromes like Lynch syndrome or familial adenomatous polyposis (FAP) is greater in adolescents and adults diagnosed with colorectal cancer, according to study background.
Still, patients aged 35 years or younger account for less than 1.5% of all colorectal cancer cases, according to the researchers.
“We hope that physicians and other health providers treating patients diagnosed with colorectal cancer under age 35 are aware of the high prevalence of hereditary cancer syndromes and therefore send them for genetic counseling and consideration of genetic testing,” Eduardo Vilar-Sanchez, MD, PhD, assistant professor in the department of clinical cancer prevention at The University of Texas MD Anderson Cancer Center, told HemOnc Today. “In addition, diagnosing patients with these syndromes extends the implications to other unaffected family members who will be tested as well. The importance is on the fact that these potentially undiagnosed carriers of hereditary syndromes will be diagnosed, thus providing them with the opportunity to engage in screening programs.”
Eduardo Vilar-Sanchez
Vilar-Sanchez and colleagues sought to define the clinical profile — including the extent of family cancer history and of hereditary cancer syndromes — in patients diagnosed with colorectal cancer at age 35 years or younger.
The analysis included 193 patients (mean age at diagnosis, 29 years) who underwent genetic counselling at MD Anderson from 2009 through 2013.
Overall, 67 patients (34.7%) had an identifiable hereditary cancer syndrome. Twenty-three patients had Lynch syndrome, 22 patients had mutation-negative Lynch syndrome, 16 patients had FAP, two patients had constitutional mismatch repair deficiency, two patients had biallelic MUTYH mutations and one patient had Li-Fraumeni syndrome.
Patients without a hereditary syndrome more frequently had metastatic disease, whereas patients with a heredity syndrome were more likely to present early and have a family history of cancer.
Still, 19% of those patients with the hereditary syndromes had no family history of the disease.
The researchers conceded that a limitation to their study was a lack of uniformity in the genetic testing, which could have meant that some patients were not identified as being hereditarily predisposed.
Another limitation may have been referral bias, as patients with a family history of cancer may have been referred for genetic counselling more regularly than those without a history.
“This potential population will be able to engage in life-style modifications and participate in chemoprevention studies or have access to risk-reducing surgeries to decrease and modulate their cancer risk,” Vilar-Sanchez said. “The next step is to continue doing research to determine how genetic testing using gene panels can help improving the diagnosis of genetic syndromes in this young population of patients.” – by Anthony SanFilippo
Disclosure: The researchers report no relevant financial disclosures.
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