Post-operative stereotactic radiosurgery of brain metastases: A single-center retrospective review of clinical outcomes

Aim: We sought to retrospectively report our outcomes using post-operative stereotactic radiosurgery (SRS)/stereotactic radiotherapy (SRT) in place of whole-brain radiation therapy (WBRT) following resection of brain metastases from our hospital-based community practice. Materials and Methods: A retrospective review of 23 patients who underwent post-operative SRS at our single institution from 2013 to 2017 was undertaken. Patient records, treatment plans and diagnostic images were reviewed. Local failure, distant intracranial failure and overall survival were studied. Categorical variables were analyzed using Fisher's exact tests. Continuous variables were analyzed using Mann-Whitney tests. The Kaplan-Meier method was used to estimate survival times. Results: 16 (70%) were single-fraction SRS, whereas the remaining 7 patients received a five-fraction treatment course. The median single-fraction dose was 16 Gy (range, 16-18). The median total dose for fractionated treatments was 25 Gy (range, 25-35). Overall survival at 6 and 12 months was 95 and 67%, respectively. Comparison of SRS versus SRT local control rates at 6 and 12 months revealed control rates of 92 and 78% versus 29 and 14%, respectively. Every patient with dural/pial involvement at the time of surgery had distant intracranial failure at the 12-month follow-up. Findings: Single-fraction frameless SRS proved to be an effective modality with excellent local control rates. However, the five-fraction SRT course was associated with an increased rate of local recurrence. Dural/pial involvement may portend a high risk for distant intracranial disease; therefore, it may be prudent to consider alternative approaches in these cases.