Advanced Lung Adenocarcinoma with EGFR 19-del Mutation Transformed into SCC after EGFR-tyrosine Kinase inhibitors Treatment: A Case report.

Background: Epidermal growth factor receptor tyrosine kinase inhibitors (EGFR-TKIs) significantly improve the survival of patients with Epidermal growth factor receptor (EGFR) sensitive mutations in non-small cell lung cancer (NSCLC).

Case Summary: A 67-year-old female patient in advanced lung adenocarcinoma suffered from drug resistance after EGFR-TKIs treatment. Secondary pathological tissue biopsy confirmed squamous cell carcinoma (SCC) transformation. Patients inevitably encountered drug resistance issues after receiving EGFR-TKIs treatment for a certain period of time, while EGFR-TKIs can significantly improve the survival of patients with EGFR-sensitive mutations in NSCLC. Notably, EGFR-TKIs resistance includes primary and acquired. Pathological transformation is one of the mechanisms of acquired resistance in EGFR-TKIs, with SCC transformation being relatively rare. Our results provide more detailed results of the patient's diagnosis and treatment process on SCC transformation after EGFR-TKIs treatment for lung adenocarcinoma.

Conclusion: Squamous cell carcinoma transformation is one of the acquired resistance mechanisms of EGFR-TKIs in advanced lung adenocarcinoma with EGFR mutations.