Cluster analysis of deterioration sites after first-line epidermal growth factor receptor-tyrosine kinase inhibitor in epidermal growth factor receptor mutated non-small cell lung cancer

Introduction
For epidermal growth factor receptor (EGFR) mutated non-small cell lung cancer (NSCLC), no studies have treated the site of recurrence after first-line tyrosine kinase inhibitor (TKI) treatment as a “metastasis pattern”. This study aims to assess whether these patients have a specific “metastasis pattern” at the site of recurrence after the treatment.

Material and methods
Data were collected from all consecutive EGFR mutated NSCLC patients between 2009 and 2021. Metastatic patterns were analyzed using cluster analysis in patients with EGFR mutated NSCLC.

Results
During the study period, 83 EGFR mutated NSCLC patients were treated with EGFR-TKI. Patients who had no metastases at the time of diagnosis were divided into two groups according to the presence or absence of recurrence of metastases after TKI administration. Patients with metastases at diagnosis were divided into 4 groups by cluster analysis. A statistically significant difference in metastasis frequency was confirmed among these 6 groups (2 test, p = 0.0001). Furthermore, when the frequency of metastasis recurrence after TKI administration in these 6 groups was examined, a statistically significant difference was confirmed (2 test, p = 0.0001).

Conclusions
Even in EGFR mutation-positive patients, the knowledge of the recurrent patterns might be useful for clinical practice in the foreseeable future, as it enables more efficient detection of metastatic disease through imaging, and more effective treatment at predicted metastatic sites.