EGFR and neoplasm: At present, the National Comprehensive Cancer Network guidelines recommend ctDNA assays to test for driver mutations, such as EGFR, ALK, ROS1, KRAS, BRAF, MET, RET, and NTRK, in instances where a patient is unfit to undergo invasive tumor biopsy, as well as for testing for acquired resistance mutations, such as EGFR T790M.