EGFR and lung cancer: Although the exact frequency of EGFR-KDDs is uncertain in the absence of routine diagnostic NGS, multicentre studies have reported EGFR-KDDs at 0.2% (n = 1510) [70] and 0.24% (n = 5394) [68] of EGFR-mutant NSCLC patients, indicating that duplications may be one of the rarest types of EGFR mutation in lung cancer.