EGFR and lung cancer: As the pathogenesis of cancer continues to clarify, many biological targets including epidermal growth factor receptor (EGFR) have been identified playing a key role in the development of a number of the most lethal cancers, and the activity of EGFR-specific tyrosine kinase inhibitors (TKIs) against such cancers ushered in an era of genotype-directed targeted therapy that fundamentally changed the overall approach to lung cancer.5