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 follow-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 irradiation sessions averaged 36.2%. Overall survival at 3, 6, 12 months was 70, 57.7 and 52%, respectively. 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 neurological status of patients.