EGFR and lung carcinoma: The guideline of the College of American Pathologists, International Association for the Study of Lung Cancer, and Association for Molecular Pathology recommends that the assay for the EGFR T790M resistant mutation is able to detect the mutation in as few as 5% of cells or less (assuming heterozygosity, a 2.5% mutant allele fraction) in clinical practice [50].