The role of cyberknife radiosurgery/radiotherapy for brain metastases of multiple or large-size tumors.

OBJECTIVE

Focused, highly targeted radiosurgery and fractionated radiotherapy using the Cyberknife are useful treatments for multiple or large metastases. Here we present our results of Cyberknife radiosurgery for 71 patients with 148 metastatic brain lesions.

METHODS

There were 32 women and 39 men with a median age of 63 (range: 30-88) years. Radiographic follow-up was available for 60 patients with 104 lesions. The mean and median initial volumes of the tumor per lesion were 6.6 and 2.9 cm(3) (range: 0.1-53.2 cm(3)), respectively, at the time of the initial Cyberknife treatment. Forty patients (56%) had a single lesion, and 31 (44%) had multiple lesions (range: 2-7) at initial treatment. The number of fractions ranged from 1 to 3, and forty (27%) of 148 lesions were treated by a fractionated course of Cyberknife therapy. The mean marginal dose was 20.2 Gy (range 7.8-30.1 Gy, median: 20.7 Gy).

RESULTS

At 44 weeks of median follow-up, there were no permanent symptoms resulting from radiation necrosis. Overall 6-month and 1-year survival rates were 74% and 47%, respectively, and the median survival time was 56 weeks. The Karnofsky performance score and extracranial metastasis were significant prognostic factors at 6 months and 1 year, respectively, in both univariate and multivariate analyses. Age or multiple metastases did not influence prognosis at 6 months and 1 year. Local control was achieved in 83% (86 lesions). After additional radiosurgical or surgical salvage, no patient died as a result of intracranial disease. Twenty-five patients developed 92 new metastases (range 1-13) outside of the treated lesions with 22.4 weeks of median follow-up. Among them, 21 patients (84 lesions) were treated by salvage Cyberknife.

CONCLUSION

Despite the inclusion of an unfavorable group of patients with large tumors, our results for survival and tumor control rates are comparable to those of published series. The Cyberknife provides the advantage of allowing for fractionated treatment to multiple or large-size tumors.