Mutation tests (also known as molecular profiling) are very specific and look for certain changes in a person's cancer genes. In these cases, a small piece of the cancer is taken and run tests on it to find out a patient's tumour cells mutation status.12
12. ACS. Tests for Non-Small Cell Lung Cancer. Available at: https://www.cancer.org/cancer/non-small-cell-lung-cancer/detection-diagnosis-staging/how-diagnosed.html. Accessed 2: May 2019.