Pivotal studies indicate a role of excision repair cross-complementation 1 (ERCC1) gene and ribonucleotide reductase M1 (RRM1) gene in conferring a differential sensitivity to cytotoxic chemotherapy and epidermal growth factor receptor (EGFR) gene has been recently extensively investigated in non-small-cell lung cancer (NSCLC).

A large body of experimental and clinical work supports the view that EGFR is a relevant target for cancer therapy. The development of selective tyrosine kinase inhibitors has become an important area of drug discovery for the treatment of a variety of solid tumors such as breast, ovarian and colorectal cancers, NSCLC, and carcinoma of the head and neck.