EGFR and neoplasm: While a variety of mutation testing modalities can be used to detect EGFR mutations, it is recommended that assays are sensitive enough to detect alterations in formalin-fixed paraffin-embedded (FFPE) specimens with tumor cell content as low as 20% [25], and that all activating EGFR mutations in exons 18–21 with a prevalence of at least 1% are covered by the assay.