Two or more different epidermal growth factor receptor (EGFR) mutations can be detected within a single tumor sample, which represents complex mutations.
Thus, the association between diverse activating mutations in EGFR and other subclonal mutations within a single tumor supports an intrinsic mechanism for proliferative and clonal diversification with broad implications in resistance to treatment.
In most of these tumors, cells that exhibited EGFR overexpression and gene amplification were distributed heterogeneously, even within a single tumor nodule.