Two-stage Gamma Knife radiosurgery for brain metastases

The aim of this study was to assess the efficacy and safety of two-stage stereotactic radiosurgery using Gamma Knife for treatment of brain metastases. Staging was applied to patients with large metastases, as well as to metastases located near critical structures. In a group of 31 patients, treatment was carried out in 2 stages with 2-4 weeks interval. The mean tumor volume at the time of the first radiosurgery was 10.4 cm3 (0.52 to 19.07; 95% CI: 8.2-12 cm3). The marginal dose at the first and second stages of radiosurgery ranged from 12 to 14.4 Gy, respectively. Median fol-low-up time was 169 days. Overall survival rate, local control, the incidence of complications, as well as changes in functional status were evaluated. Decrease in volume of tumors between irra-diation sessions averaged 36.2%. Overall survival at 3, 6, 12 months was 70, 57.7 and 52%, re-spectively. Local control after 3, 6, 12 months was 92, 87 and 66%, respectively. Radionecrosis was found out in 2 patients. Increase of Carnovsky index in study group after treatment was by an average of 10 points (p=0.007). Thus, two-stage trained stereotactic radiosurgery can be a safe and effective alternative to surgical treatment of brain metastases without worsening the neuro-logical status of patients.