Frameless single-isocenter intensity modulated stereotactic radiosurgery for simultaneous treatment of multiple...

Stereotactic radiosurgery (SRS) is well accepted treatment for patients with intracranial metastases, but the role of frameless radiosurgery is not well defined. Here, we describe our clinical experience applying a novel single-isocenter technique to frameless intensity modulated stereotactic radiosurgery (IMRS) for simultaneous treatment of multiple intracranial metastases.

Between 2006 and 2012, 100 consecutive patients received frameless IMRS for multiple intracranial metastases using a single, centrally-located isocenter. Among these, 29 patients were treated for progressive or recurrent intracranial disease. A total of 465 metastases (median, 4 per patient, range, 2-18) were treated to a median dose of 20 Gy (range, 15-50 Gy). Follow-up including clinical examination and magnetic resonance imaging (MRI) occurred every 3 months.

Median follow-up for all patients was 4.3 months (range, 0.2-58.3 months), with 83 patients (83.0%) followed until their death. For the remaining 17 patients alive at the time of analysis, median follow-up was 9.2 months (range, 2.2-58.3 months). Overall survival at 6 months was 49.5% [95% confidence interval (CI), 35.3-63.6%]. Local control at 6 and 12 months was 88.9% (95% CI, 79.1-98.6%) and 81.5% (95% CI, 65.2-97.7%), respectively. Regional failure was observed in 39 patients (39%), and 25 patients (25%) received salvage therapy. Grade 3 or greater treatment-related toxicity was observed in 4 patients (4%) and included intracranial hemorrhage, seizure, and radionecrosis. Median total treatment time was 17.2 minutes (range, 2.8-55.3 minutes).

Single-isocenter IMRS for multiple intracranial metastases can produce clinical outcomes comparable to those of conventional radiosurgery techniques.