New Genetic Testing Method Can Improve Cancer Detection

A large proportion of cancer patients carry genetic variants of unknown significance.

A newly developed process can identify mutations and prioritize gene variants in breast and ovarian cancer that were previously missed by conventional genetic testing, according to a study published in BMC Medical Genomics.

In southwestern Ontario, Canada, approximately 16 to 20% of women who had their BRCA genes tested were found to carry a variant that is already well understood by clinicians and genetic counselors. This allows doctors to decide whether or not to proceed with certain treatments.

The remaining 80 to 84% of women carry gene variants of uncertain significance, leaving an unclear path for how patients and doctors should proceed. At this time, there are no standard agreements on how to diagnose these patients.

A new detection method was first applied to 102 people who were at risk or had a diagnosis of inherited breast cancer. There were 15,311 variants identified in 7 complete genes, and after the analysis was finished, between 0 and 3 variants were prioritized in most of the participants.

“When a woman with a family history of breast cancer sees her physician, they want to know if they have a mutation in breast/ovarian cancer genes,” said lead researcher Peter Rogan, PhD. “All of the patients that we studied had been sequenced for BRCA1 or BRCA2. The causative cancer gene variants are hiding in plain sight in these and other cancer genes, but the original testing laboratory didn't recognize them. Our approach can reveal gene variants that might explain their increased risk for cancer.”

If the method is applied, it could reduce the number of possible variants that need to be investigated, while also increasing the amount of patients who are properly diagnosed.

In order to increase the benefit from genetic testing for breast cancer, researchers believe that doctors and policymakers should include additional genes in testing and consider new approaches that can interpret complete gene sequences.