Stereotactic radiosurgery for brain metastases: A retrospective cohort study comparing treatment results between two lung cancer patient age groups, 75 years or older vs 65–74 years

Background: There is little information on stereotactic radiosurgery (SRS) results for brain metastases (BMs) in lung cancer patients ≥75 years of age. We aimed to reappraise whether SRS results for patients ≥75 (very elderly) differ from those of patients with 65−74 years old (elderly). Methods: This IRB-approved retrospective cohort study was based on our prospectively-accumulated database including 7351 consecutive patients undergoing gamma knife (GK) SRS performed for BMs by two highly experienced neurosurgeons during the 1998–2018 period. We selected a total of 2915 elderly patients (age ≥65 years, 39.7 % of the 7351) with lung cancers (902 females, 2013 males, median age; 72 [maximum; 96] years, 2441 NSCLCs, 474 SCLCs) for this study. Results: Post-SRS median survival times (MSTs, months) differed significantly between the two lung cancer types, NSCLC (9.0) and SCLC (7.2, p < 0.0001). In NSCLC patients, post-SRS MSTs were significantly shorter in the very elderly (9.7) than those in the elderly (7.8) group (p < 0.0001). However, in SCLC patients, there were no significant MST differences (7.3 vs 6.9, p = 0.52) between the two age groups. In both NSCLC and SCLC patients, neither crude nor cumulative incidences of secondary endpoints in the very elderly group, i.e., neurological death, neurological deterioration, local recurrence, repeat SRS, salvage whole brain radiotherapy and SRS-related complications, were shown to be unfavorable to those in the elderly group. Conclusions: Our results suggest that carefully-selected patients ≥75 years of age are not poor candidates for SRS as compared to those 65−74 years old.