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Expansion of genetic testing feasible for familial CRC
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Genetic susceptibility is common in early-onset familial colorectal cancer, suggesting an expansion of genetic testing is warranted, according to new research data.
“Knowing which cancer gene has caused bowel cancer isn’t just important for researchers — it’s crucial for the treatment, counseling and surveillance of patients and their relatives,” Richard S. Houlston, MD, PhD, professor of molecular and population genetics at The Institute of Cancer Research, said in a press release. “Our study has found that using just existing tests for known cancer genes, we could identify the genetic causes of familial bowel cancer in perhaps as many as a quarter of cases.”
Richard S. Houlston
Aiming to quantify the impact of genetic mutation in familial CRC risk, Houlston and colleagues performed genetic sequencing in 626 patients with a family history of CRC and at least one first-degree relative with CRC between 2003 and 2011 obtained through the U.K. population-based National Study of Colorectal Cancer Genetics registry.
They found the most common mutations to be in mismatch repair genes (APC, MUTYH, and SMAD4/BMPR1A), contributing to 10.9% of familial CRC cases. Furthermore, mutations in other known CRC genes contributed to 3.3% of cases, and three patients with family histories of CRC had POLE/POLD1 exonuclease domain mutations. Overall, mutations in known genes accounted for 14.2% of familial CRC (95% CI, 11.5-17.2).
“It’s vital that we improve access to genetic testing for cancer patients and their relatives so as many as possible can have a genetic diagnosis,” Houlston said. “Of course, we are still left with three-quarters of patients where no genetic cause could be identified, and that underlines the need for further research to identify new cancer genes.”
“So far, there are 10 gene faults that we know are linked to inherited bowel cancer,” Aine McCarthy, PhD, science information officer for Cancer Research UK, said in the release. “People with these gene faults have a much higher risk of developing the disease and so are screened from a younger age. But this research shows that around three-quarters of people with a family history of bowel cancer do not have these known gene faults. By testing a much larger portion of their DNA we may be able to discover other mistakes in different genes that can also cause bowel cancer. This could potentially help doctors decide how best to monitor people for early signs of bowel cancer and guide their treatment.”
Disclosure: The researchers report no relevant financial disclosures.
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