EGFR and cancer: 40 Exon 20 insertions (ex20ins), which are presentin roughly 10% of mutant EGFR NSCLC cases, are another less frequentmutation.41,42 Other rare EGFR mutations include S768I,G719X, and L861Q.43 All of these mutationsare considered to as activating mutations because they enable EGFRto signal more frequently and consistently, which could result inthe development and spread of cancer.