Several rare inherited EGFR variants are associated with lung cancer risk78; while the mechanism through which these variants increase disease risk is not confirmed, one possibility might be that the mutation causes genetic instability that predisposes cells to somatic mutations and tumourigenesis20; for example, the T790M variant in EGFR is both a germline variant associated with lung cancer and an important somatic variant with implications for therapy.79 80 The rarity and unclear penetrance of germline EGFR mutations makes discovery and subsequent management challenging. This evidence concerns the gene EGFR and lung cancer.