In lung cancer patients, it is important to test for “targetable mutations” in the cancer tissue. Targetable mutations are specific DNA changes to cancer cells that cause specific proteins to signal cancer cells to grow. These are important to test for because we have medications that turn off these proteins that are more effective than chemotherapy, if these mutations are identified. We work closely with our radiology and pulmonology department to try to get enough tissue from a lung mass to test for these cases, but sometimes due to patient safety, we cannot get enough tissue.
Our doctors have already been using blood testing to help find these mutations when we cannot check the cancer tissue itself. These blood tests evaluate “circulating tumor cells” in the blood stream and then can amplify those cells’ DNA to test. The largest analysis of these tests showed that we can identify mutations in the bloodstream of 85% of all advanced tumors and the accuracy compared to testing the tumor itself was 90%. In patients where mutations may dictate which therapy will be the most effective, this is a great tool to help without having to put a patient through an extra biopsy.