Upfront Stereotactic Radiosurgery or Fractionated Stereotactic Radiotherapy in Elderly Patients with Brain Metastases from Non–Small Cell Lung Cancer: A Retrospective Analysis of a 10-Year Bi-institutional Experience

Purpose Stereotactic radiosurgery (SRS) or fractionated stereotactic radiotherapy (FSRT) are increasingly used as initial therapies for brain metastases (BM). We aimed to assess the outcomes of SRS/FSRT in patients aged ≥ 65 years who had 1-10 BM from non–small cell lung cancer (NSCLC). Materials and Methods We retrospectively reviewed 91 elderly NSCLC patients with 222 BM who were treated with SRS/FSRT at two institutions between 2010 and 2020. The primary endpoint was overall survival (OS) after SRS/FSRT. In addition, in-field local control (IFLC) within the treated field was evaluated. Statistical analysis was performed to identify the prognostic factors affecting OS and IFLC. Results During a median follow-up of 18 months, the median OS was 32 months. The 1- and 2-year survival rates were 69.8% and 56.1%, respectively. In multivariate analysis, the NSCLC-specific graded prognostic assessment (GPA) score (p=0.007) and administration of systemic therapy (p=0.039) were defined as prognosticators affecting OS. The median IFLC period was 31 months, and the 1- and 2-year IFLC rates were 75.9% and 57.6%, respectively. The total BM volume (p=0.042) significantly affected IFLC. No severe adverse events were reported after SRS/FSRT. Conclusion SRS/FSRT is an effective upfront treatment option for BM arising from NSCLC in elderly patients, with a good OS without severe side effects. Higher GPA score and active systemic treatment were associated with improved OS, indicating that elderly patients are significant candidates for SRS/FSRT.