Researchers within the Mayo Clinic Center for Individualized Medicine have found that 1 in 6 patients with colorectal cancer have a hereditary cancer-related gene mutation.
Colorectal cancer (CRC) is the third most common cancer in men and second most common cancer in women. Recent reports have shown that cases among individuals under 50 have been increasing. Evidence has also shown that the rates of cases and deaths differ among racial and ethnic groups, being specifically higher in Black people.
Hereditary factors play a key role in the risk of developing many cancers and CRC is no exception. Identifying the genes that play a role in the development or inheritance of cancer is important in the selection of treatments and the screening of affected populations. Previous estimates have indicated that at least 10% of CRC patients have a germline genomic alteration. However, these studies have focused on registry populations, genetic testing company databases, high risk cancer clinics, and the use of relatively small gene panels. With the emergence of targeted therapies, researchers have questioned whether a broad-based universal germline genetic test may have clinical implications in solid tumours.
Prevalence of pathogenic germline variants
In this study, published in Clinical Gastroenterology and Hepatology, researchers undertook a prospective multi-site study of germline sequencing. They specifically used an NGS sequencing panel with over 80 cancer predisposition genes in 361 CRC patients receiving care at Mayor Clinic Cancer Centers.
The researchers found a pathogenic germline variant in 15.5% of patients, including 44 in moderate and high penetrance cancer susceptibility genes. In addition, they found that 34 patients had clinically actionable findings that would not have been detected by standard approaches, including a CRC specific gene panel. Most importantly, they found that based on the genetic findings, 11% of patients had modifications in their treatment.
These findings emphasise the power of genetics in allowing us to detect heritable mutations and thus identify high-risk individuals. Targeted cancer screening can help prevent cancer altogether in the next generation of affected families. Unfortunately, in this study, only 16% of family members underwent free genetic testing, suggesting that there are other nonfinancial barriers that need to be explored further.
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