Tyrosine kinase inhibitors (TKI) have greatly improved prognosis of epidermal growth factor receptor (EGFR)-positive non-small cell lung cancer (NSCLC), with tumor responses in the majority of cases and a median overall survival currently exceeding 2.5 years. However, clinical courses vary widely and eventual treatment failure is inevitable. The most common resistance mechanism against first- and second-generation EGFR inhibitors is the EGFR T790M mutation, which emerges in about 50% of cases and is amenable to next-line treatment with the third-generation compound osimertinib. However, experience in everyday clinical practice shows that implementation of EGFR TKI sequencing is often problematic, for example because a considerable number of EGFR+ NSCLC patients failing first- and second-generation EGFR inhibitors do not undergo T790M mutation testing at the time of disease progression. This study will use patient records to analyze the clinical course of EGFR+ NSCLC patients treated with first- and second-generation EGFR inhibitors at the Thoraxklinik Heidelberg (Germany) during the past years. The main aim is to analyze the diagnostic and therapeutic measures, including implementation of osimertinib, taken at the time of disease progression as well as their effect on patient outcome in a real-world, routine clinical setting.

Inclusion Criteria:

• histologically confirmed locally advanced (stage III) and not suitable for definitive local treatment, or metastatic (stage IV) NSCLC
• activating EGFR mutation confirmed
• treatment with EGFR TKI

Exclusion Criteria:

none

All NSCLC patients with activating EGFR mutations treated with EGFR TKI at the Thoraxklinik Heidelberg between 2010 and 2019.