Intracranial chordomas are rare tumors arising in the midline structures of the skull base. Although considered biologically benign tumors, these tumors are locally aggressive with invasive growth within mesenchymal derived tissues. Recurrences are frequently emerging even after radical surgery of these tumors. Unfortunately, chordomas respond poorly to conventional radiotherapy and therefore linac-based radiosurgery, proton-beam radiotherapy has been tried for these patients.

     In this study we report the long term results of adjuvant treatment with the gamma knife for thirteen patients with intracranial chordoma.

     Between 1984 and 2010 fifteen patients with intracranial tumors were treated with the gamma knife, but two of them were lost to follow up. The median age at diagnosis was 51 years and the median time for gamma knife treatment was 54 years.

       All patients were previously operated and had histopathological diagnosis. Most patients had conventional radiotherapy as adjuvant therapy after surgery and two patients had proton beam radiation therapy.

     The median tumor volume were 5 ml, ranging 1,3-24,3 ml. Prescription dose ranged from 12 to 20 Gy at the 40-50% isodose. Four patients were retreated with the gamma knife and one patient received three treatments. Patients were followed after diagnosis for 2 to 23 years (median 6 years) and radiologically for 1 to 21 years (median 3 years). Six of eight patients followed for five years had tumor control while one patient had tumor progression and one patient had died. After 10 years follow up two patients had tumor control, one patient had tumor progression and four patients had died due to tumor progression.

     This was a retrospective study.

     Gamma knife radiosurgery can be a useful tool for chordoma remnants after microsurgery. 5-years tumor control rate is approximately 75% (6/8 patients) after gamma knife radiosurgery.

     However, most patients have a progressive disease within 10 years after treatment.