Transformation of lung adenocarcinoma into small cell lung cancer after treatment with epidermal growth factor receptor tyrosine kinase inhibitors

Epidermal growth factor receptor tyrosine kinase inhibitors effectively improve the prognosis of patients with epidermal growth factor receptor–mutant lung adenocarcinoma. However, acquired resistance inevitably develops with small cell lung cancer transformation emerging as a rare but increasingly frequent mechanism of tyrosine kinase inhibitor resistance. This transformation poses significant challenges to the health of patients with lung cancer and complicates their clinical management. This article comprehensively reviews the diagnostic, predictive, mechanistic, and therapeutic aspects of small cell lung cancer transformation to enhance our understanding and clinical awareness of this phenomenon.