Though non-EGFR patients have been reported to have NSCLC to SCLC transformation, this phenomenon occurs at a much lower frequency, and non-EGFR transformations most often occur in heavy smokers, whereas EGFR-driven SCLC transformation often occurs in former or never-smokers, as reported by Ferrer et al. [25]. This evidence concerns the gene EGFR and small cell lung carcinoma.