EGFR mutations in non-small cell lung cancer: an audit from West China Hospital

To discover the incidence and characteristics of EGFR mutations in non-small cell lung cancer (NSCLC) in a single, large cohort as a part of routine diagnostic investigations.

We reviewed EGFR mutations investigated by Amplification Refractory Mutation System (ARMS) PCR (covering 29 known mutations) using DNA samples from FFPE tissue or cell clot specimens in a total of 3894 cases of NSCLC analysed between 2012-2014.

EGFR mutations are preferentially associated with adenocarcinomaand adenosquamous histology, particularly those well to moderately differentiated, and were significantly more common in female than male patients irrespective of histological subtypes. Exon 19 deletion (45.7%) and exon 21 L858R (45.6%) accounted for the vast majority of the EGFR mutations detected, with the remaining mutations being infrequent (<2%). Compound mutations were seen in 51 (3%) of the mutant cases, the combination of these compound mutations could be classified into three subgroups according to the potential impact of individual mutations on EGFR TKI therapy. Accordingly, 7 cases had both sensitive mutations, 4 cases harboured one sensitive and one less responsive /uncertain mutation, 19 cases contained one sensitive and one resistant change, and a further 21 cases had two less responsive /uncertain mutations.

Our data represents the largest EGFR mutation survey based on routine clinical diagnostic laboratory data from a single institution, it confirms the incidence and characteristics of EGFR mutations in NSCLC seen in Asian patients, and also unravels the combinatorial nature of rare compound EGFR mutations.