Researchers say offering this type of advanced genetic testing diagnosis could help guide and expedite treatment decisions for patients who have CRC while simultaneously identifying those who also are likely to have Lynch syndrome (LS), which occurs when a person inherits a mutation in one of the DNA repair genes. Individuals with LS are much more likely to develop CRC, uterine, ovarian, stomach and other cancers than the general population.
For this study, researchers wanted to know if an upfront tumor-sequencing approach using a single test that screens for multiple mutations could replace the current multi-test screening approach commonly used to determine whether a patient has LS. To do this, researchers analyzed tumor samples from 419 CRC patients who participated in the Ohio Colorectal Cancer Prevention Initiative (OCCPI), a statewide research study to screen newly diagnosed CRC patients and their biological relatives for LS. A validation cohort of 46 patients with CRC and known to have LS also was included.
All OCCPI study participants had their tumor samples analyzed using the traditional multi-test genetic testing approach and the single, upfront genomic tumor-sequencing testing approach, in which a single tumor sample was analyzed for multiple mutations simultaneously. Researchers compared results from the two screening methods and found that the upfront tumor-sequencing approach was more sensitive and specific for detecting LS than the old, multiple-test model. Tumor sequencing resulted in a 10% improvement in LS detection rates while also providing important information about treatment options for the patients.
“Testing methods of the past would just point to a suspicion of Lynch syndrome, but they could not confirm the diagnosis without multiple additional tests, which slows down the diagnostic process and adds costs,” says Heather Hampel, MS, LGC, corresponding author of the study and principal investigator of the OCCPI.
“This new approach points to the exact mutation patients were born with and does so through a single test,” she adds. “The mutation will need to be confirmed using a blood test, but this requires a single mutation test, which is less expensive than multi-gene panel testing.
Published in the journal JAMA Oncology.