During the last 8 years (12/93–10/01) 11 patientswith skull base chordoma and 2 patients with skull base chondrosarcoma were treated in our department of Na Homolce Hospital. Twelve patients (ten with chordoma, both with chondrosarcoma) underwent Gamma knife radiosurgery, one patient’s chordoma was only diagnosed by stereotactic biopsy in our department. In a group of 12 patients (5women, 7 men) treated by radiosurgery the age varied from 25 to 61 years (median 42). Twelve patients underwent partial resection before stereotactic radiosurgery, three patients were reoperated, one patient had a ventriculoperitoneal shunt because of hydrocephalus, two patients underwent stereotactic biopsy. The minimal dose to the margin was 11–27,5 Gy (median 16,5), the median tumor volume was 12 000 mm3. The follow-up evaluation was 19–106 months (median 50). Eight patients showed clinical improvement, three worsened clinically, and one died. One patient who died had tumor progression remote from the radiosurgery volume. Post radiation follow-up imaging showed a reduction in tumor size in five patients (42 %), no further tumor growth in three patients (25%), an increase in the size of the tumor in four patients (33 %). One of the three patients with worsening of their clinical status and further tumor growth underwent repeated resection. The patient’s clinical state was then compensated. A symptomatic treatment was only possible in the two remaining patients. Skull base chordomas and chondrosarcomas are invasive tumors suitable for the combined surgical and radiation treatment. It is appropriate for their critical location, locally aggressive behaviour, and high recurrence rate. Our results proved in a group of 12 patients to the value of stereotactic radiosurgery as an adjuvant radiation treatment .

        Key words: chordoma, chondrosarcoma, radiosurgery, stereotactic biopsy