According to researchers from the University of Oklahoma, next-generation sequencing is more effective at identifying patients with high levels of microsatellite instability than immunohistochemistry (IHC). This finding, published in Cancer Cell, could lead to thousands more cancer patients receiving the most effective treatment for their condition.
The study focused on identifying high levels of microsatellite instability (MSI) in newly diagnosed cancer patients, which indicates a person's DNA has lost the ability to fix its own errors during replication. MSI is crucial to identify as patients with this condition are more likely to respond to immunotherapy drugs rather than other cancer treatments.
The team compared the two tests, IHC and NGS, to determine the most effective method for identifying MSI. IHC looks for mismatch repair proteins, while NGS is a broader approach that tests for genetic mutations associated with MSI.
The results showed that NGS identified more patients with MSI than IHC. Although IHC is currently the more commonly used test, the study suggests that a shift toward NGS could result in more accurate diagnoses and treatments.
In 2022, U.S. oncologists diagnosed 151,030 new cases of colon cancer and 65,950 new cases of endometrial cancer. Had NGS been used in combination with standard IHC testing, doctors would have discovered MSI in 1,510 additional cases of colon cancer and 3,891 additional cases of endometrial cancer.
“Although IHC catches most cancer patients with high microsatellite instability, it doesn’t identify everyone,” co-author Abdul Rafeh Naqash explained, “and we want as many as possible to receive the immunotherapy that can greatly reduce their cancer and, in some cases, eliminate it.”