Hereditary evaluation and genetic counselling in young individuals with colorectal cancer in a population-based cohort

Aim: Early-onset colorectal cancer should raise suspicions of a hereditary colorectal cancer (CRC) syndrome, including Lynch syndrome (LS) and Familial Adenomatous Polyposis (FAP). Collection of family history and genetic counselling (GC) is mandatory but previous studies have revealed low awareness of hereditary CRC among clinicians why there has been an incentive to implement universal LS screening. In this population-based cohort study, we aimed to observe the uptake of GC in the Swedish South-Eastern medical care region for young CRC patients and to investigate the frequency of patients diagnosed with LS.

Methods: Patients below 50 years of age diagnosed with CRC between 2008 and 2017 were identified from the national Swedish Colorectal Cancer Registry. Medical records were reviewed regarding family history, co-morbidity and referral for GC, with a follow-up time of at least three years.

Results: The analysis included 278 patients with 287 tumours, 108 (38%) located in rectum and 179 (62%) in colon. One hundred sixteen (42%) individuals were referred to the Regional Clinical Genetics service, whereof 74 (27%) underwent complete investigation. Thirteen (18%) patients were identified with a mutation, eleven (15%) had LS and two (3%) FAP. The remaining 61 (82%), without proven mutation, were considered as familial CRC. Younger age correlated with a higher chance of referral for GC.

Conclusion: The study found that only a minority of young CRC patients underwent genetic counselling, contrary to clinical guidelines. Hereditary CRC is therefore probably underdiagnosed even among young individuals.