Complications after stereotactic radiosurgery for brain metastases: Incidences, correlating factors, treatments and outcomes

Background and purpose: Complications after stereotactic radiosurgery (SRS) for brain metastases (BMs) were analyzed in detail using our database including nearly 3000 BM patients. Materials and methods: This was an institutional review board-approved, retrospective cohort study using our prospectively accumulated database including 3271 consecutive patients who underwent gamma knife SRS for BMs during the 1998–2016 period. Excluding four patients lost to follow-up, 112 with three-staged treatment and 189 with post-operative irradiation, 2966 who underwent a single-session of SRS only as radical irradiation were studied. Results: The overall median survival time after SRS was 7.8 (95% CI; 7.4–8.1) months. Post-SRS complications occurred in 86 patients (2.9%) 1.9–211.4 (median; 24.0, IQR; 12.0–64.6) months after treatment. RTOG neurotoxicity grades were 2, 3 and 4 in 58, 25 and 3 patients, respectively. Cumulative incidences determined with a competing risk analysis were 1.4%, 2.2%, 2.4%, 2.6% and 2.9% at the 12th, 24th, 36th, 48th and 60th post-SRS month, respectively. Among various pre-SRS clinical factors and radiosurgical parameters, multivariable analyses demonstrated solitary tumor (Adjusted HR; 0.584, 95% CI; 0.381–0.894, p = 0.0133), controlled primary cancer (Adjusted HR; 2.595, 95% CI; 1.646–4.091, p < 0.0001), no extra-cerebral metastases (Adjusted HR; 1.608, 95% CI; 1.028–2.514, p = 0.0374), KPS ≥80% (Adjusted HR; 2.715, 95% CI; 1.245–5.924, p = 0.0121) and largest tumor volume ≥3.3 cc (Adjusted HR; 0.516, 95% CI; 0.318–0.836, p = 0.0072) to be independently significant predictors of a higher incidence of complications. Conclusion: The post-SRS complication incidence is acceptably low (2.9%). Meticulous long-term follow-up after SRS is crucial for all patients.