Frameless Stereotactic Radiosurgery for Treatment of Intracranial Metastases

A.K Olson; M.C Smith; T.C Ryken; P.W Hitchon; E.C Pennington; B.J Smith; J.E Bayouth; J.M Buatti

doi:10.1016/j.ijrobp.2008.06.1525

Purpose/Objective(s) To assess the efficacy of frameless stereotactic radiosurgery for the treatment of metastatic brain lesions. Materials/Methods One hundred ninety-five patients with metastatic carcinoma to the brain were treated with frameless stereotactic radiosurgery (FSRS) as primary management of intracranial disease. Patients received the following treatments: 100 FSRS alone, 40 FSRS and surgery, 40 FSRS and whole-brain radiation therapy (WBRT), and 15 FSRS with surgery and WBRT. Median follow-up was 6 months. The median number of lesions was 1 (range, 1-5). The median dose was 17.5 Gy (range, 12-24 Gy). Overall survival is calculated as time from FSRS to date of death or last follow-up. Local failure-free survival is defined as time from FSRS to last scan. Overall survival and the local failure-free survival are estimated using the method of Kaplan-Meier. Cox regression is used to estimate the effect of different covariates, including the number of lesions, patient's age, treatment dose, and the percentage isodose line on the hazard of the two outcomes. All statistical tests were two-sided and carried out at the 5% level of significance. Results Overall survival at 1 and 2 years was 45% and 19% with median survival of 10.1 months. Median survival by treatment group was 7.8 months for FSRS; 17.3 months for FSRS and surgery; 8.8 months for FSRS and WBRT; and 13.3 months for FSRS, surgery, and WBRT group. Estimated 1- and 2-year local failure-free rates were 77% and 75%, respectively. A total of 12.8% (25/195) of patients experienced local failure: 15% (15/100) with FSRS, 7.5% (3/40) with FSRS and surgery, 10% (4/40) with FSRS and WBRT, and 20% (3/15) with FSRS, surgery, and WBRT. Overall survival was significantly improved in patients treated with FSRS and surgery versus FSRS alone (p < 0.0001). Local control was not significantly different among treatment groups. Overall survival and local failure-free survival were not improved with the addition of WBRT in patients treated with FSRS or FSRS and surgery. Conclusions This is the largest reported series of frameless stereotactic radiosurgery for intracranial metastases. Using FSRS allows patients to avoid ring placement and appears to produce excellent local control comparable to frame-based systems from historic series. All treatment combinations yielded similar local control suggesting that SRS alone or in combination with surgery is acceptable and that adding WBRT did not improve outcome in our selected patient series.

Frameless Stereotactic Radiosurgery for Treatment of Intracranial Metastases

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