Genetic testing of colorectal cancer of low value before the age of 40

A study published in Molecular Genetics & Genomic Medicine concludes that the chance of detecting a hereditary cancer syndrome in young colorectal cancer patients is low. The study was enabled by the SciLifeLab National Genomics Infrastructure (NGI).

Colorectal cancer is the third most common cancer diagnosed in Sweden. Development of the disease before the age of 40 in persons without a family history of the disease is unusual, however.

To examine possible predisposing genetic factors behind the cancer, researchers from Karolinska Institutet used whole exome sequencing – a technique that sequence all of the protein-coding regions of genes in a genome.

Few pathogenic variants were identified. The results show that the chance of detecting a hereditary cancer syndrome in patients with colorectal cancer at young age, but without family history, was 2 out of 51 – or 4 percent – in this case. The authors therefore suggest that genetic testing in this patient group is of limited value.