Clinical Results and Hematologic Predictors of Linear Accelerator–Based Stereotactic Radiosurgery or Fractionated Stereotactic Radiotherapy for Brain Metastasis in Patients Aged 75 Years or Older: A Retrospective Study.

This study aimed to evaluate prognostic factors including pre-radiosurgical blood count in elderly patients (EPs) with brain metastasis (BM) who were treated using linear accelerator (LINAC)-based stereotactic radiosurgery (SRS) and fractionated stereotactic radiotherapy (fSRT) with a micro-multileaf collimator. Between January 2011 and November 2021, 101 consecutive EPs with BM were treated by LINAC-based SRS or fSRT using LINAC with a micro-multileaf collimator. EPs were defined as patients aged ≥75 years. The tumors originated from the lungs (n = 90; 89.1%), colon (n = 2; 2.0%), and others (n = 9; 8.8%) in these EPs. The median pretreatment Karnofsky Performance Status was 80 (range, 40–100). The median follow-up time was 10 months (range, 0–76), as was the median survival. The 6-month, 1-year, and 2-year survival in the EP group was 58.3%, 43.2%, and 28.5%, respectively. Freedom from local failure at 6 months and 1 and 2 years was 97%, 95%, and 91.5%, respectively. Freedom from distant failure at 6 months and 1 and 2 years in EPs was 70.6%, 59.4%, and 54.2%, respectively. A high neutrophil/lymphocyte ratio >5.33 was an unfavorable predictor of prognosis for EPs with BMs treated with SRS and fSRT (P < 0.001). In the EPs, the prognostic factors associated with prolonged survival in the Cox proportional hazards model were being female and a good pretreatment Karnofsky Performance Status. The findings of our study highlight the efficacy of LINAC-based SRS and fSRT with a micro-multileaf collimator in the treatment of EPs with BMs. Neutrophil/lymphocyte ratio can be an important factor in treatment decisions for EPs with BMs. [ABSTRACT FROM AUTHOR]