Stereotactic radiation therapy for progressive residual pilocytic astrocytomas

This report shows the results of stereotactic radiation therapy for progressive residual pilocytic astrocytomas. Medical records of patients who had undergone stereotactic radiation therapy for a progressive residual pilocytic astrocytoma were reviewed. Between 1995 and 2010, 12 patients with progression of a residual pilocytic astrocytoma underwent stereotactic radiation therapy at UCLA. Presentation was headache (4), visual defects (3), hormonal disturbances (2), gelastic seizures (2) and ataxia (1). MRI showed a cystic (9), mixed solid/cystic (2) or solid tumor (1); located in the hypothalamus (5), midbrain (3), thalamus (2), optic chiasm (1) or deep cerebellum (1). Median age was 21 years (range 5–41). Nine tumors received stereotactic radiotherapy (SRT). Three tumors received stereotactic radiosurgery (SRS), two of them to their choline positive regions. SRT median total dose was 50.4 Gy (40–50.4 Gy) in a median of 28 fractions (20–28), using a median fraction dose of 1.8 Gy (1.8–2 Gy) to a median target volume of 6.5 cm³. (2.4–33.57 cm³) SRS median dose was 18.75 Gy (16.66–20 Gy) to a median target volume of 1.69 cm³ (0.74–2.22 cm³). Median follow-up time was 37.5 months. Actuarial long-term progression-free and disease-specific survival probabilities were 73.3 and 91.7 %, respectively. No radiation-induced complications were observed. Stereotactic radiation therapy is a safe and effective modality to control progressive residual pilocytic astrocytomas. Better outcomes are obtained with SRT to entire tumor volumes than with SRS targeting choline positive tumor regions.