2022 Volume 70 Issue 6 Pages 397-405
Background : This study was performed to evaluate clinical practices in patients with atypical epidermal growth factor receptor (EGFR)-positive inoperable non-small cell lung cancer (NSCLC) in Nagano Prefecture, Japan.
Patients and methods : Patients with newly diagnosed atypical EGFR-positive inoperable NSCLC in 14 hospitals in Nagano, Japan, between May 2016 and March 2019 were enrolled in this study. Atypical EGFR mutations included G719X, S768I, L861Q, compound mutations, and coexistence of de novo T790N in this study. After registering baseline clinical characteristics and initial treatment, serial data were recorded every 4 months in each patient. Initial and serial therapies were at the discretion of the attending physician.
Results : The study population consisted of 24 patients with atypical EGFR-positive NSCLC (12 men and 12 women ; median age : 78.5 years ; range : 49-89 years). Fourteen patients had single G719X, S768I, or L861Q mutation and 10 had compound EGFR mutations. Performance statuses 0/1/2/3/4 were seen in 11/7/3/2/1 cases and clinical stage I/II/III/IV/ recurrence occurred in 1/0/0/15/8 cases, respectively. One patient with clinical stage IA was treated with radiotherapy. Other patients were treated with EGFR-tyrosine kinase inhibitors (TKIs) as first (n＝21) or second (n＝2)-line therapy, and the response rate to TKIs was 56.5％. Median overall survival was 23.9 months (95％ confidence interval［ CI］: 10.2 months to NA) in atypical EGFR-positive cases.
Conclusion : The present results reveal that clinical outcomes in patients with atypical EGFR- positive NSCLCs in Nagano prefecture were comparable with those in other clinical trials and studies.
