High-dose radiotherapy in the management of chordoma and chondrosarcoma of the skull base and cervical spine: Part 1--Clinical outcomes.

AIMS: Patients with chordoma and chondrosarcoma in the skull base present a complex multidisciplinary problem. These tumours are rare and occur in difficult anatomical regions. We reviewed the local control and survival of patients treated in our centre.
MATERIALS AND METHODS: Between 1996 and 2005, 12 adult cases of chordoma (nine) and chondrosarcoma (three) in the skull base or cervical spine were treated in our centre. The median follow-up is currently 38 months. One patient was treated with palliative intent. In 10 cases the prescription dose was 65 Gy in 39 fractions. The target volumes were measured, and the target maximum and minimum doses and the equivalent uniform dose (EUD) for the phase I plans were recorded.
RESULTS: Local control was achieved in 11 of 12 cases. One chordoma patient failed locally, and one other died of metastatic disease despite local control. The 3- and 5-year cause-specific survival for the series was 88 and 75%, respectively. The mean phase I planning target volume (PTV) was 120.4 cm(3). The median minimum dose in the phase I PTV was 81.0%. The median EUD (expressed as a percentage of the prescribed dose) for the phase I PTV, calculated using a value for the exponent a of -15, was 98.3%. The phase I EUD was below 80% in two of the 12 cases.
CONCLUSIONS: Our results confirm a need for aggressive local surgery and high-dose radiotherapy, and endorse multidisciplinary working. Although charged particle therapy is accepted as providing optimal treatment plans, in eight of our patients travel abroad would not have been feasible. This series provides encouraging results for carefully planned photon conformal radiotherapy, carried out in close collaboration with a specialist surgical team.