Fractionated carbon ion irradiation of skull base tumors at GSI. First clinical results and future perspectives

Background: Radiobiological and physical examinations suggest clinical adva ntages of heavy ion irradiation. We report the results of 23 women and 22 m en (median age 48 years) with skull base tumors irradiated with carbon ion beams at the Gesellschaft fur Schwerionenforschung (GSI), Darmstadt, from D ecember 1997 until September 1999. Patients and Methods: The study included patients with chordomas (17), chon drosarcomas (10) and other skull base tumors (Table 1). It is the first tim e that the intensity-controlled rasterscan-technique and the application of positron-emission tomography (PET) for quality assurance was used. All pat ients had computed tomography for three-dimensional-treatment planning (Fig ure 1). Patients with chordomas and chondrosarcomas underwent fractionated carbon ion irradiation in 20 consecutive days (median total dose 60 GyE). O ther histologies were treated with a carbon ion boost of 15 to 18 GyE deliv ered to the macroscopic tumor after fractionated stereotactic radiotherapy (median total dose 63 GyE). Results: Mean follow-up was 9 months. Irradiation was well tolerated by all patients. Partial tumor remission was seen in 7 patients (15.5%) (Figure 2 ). One-year local control rate was 94%. One patient (2.2%;) deceased. No se vere toxicity and no local recurrence within the treated volume were observ ed. Conclusion: Clinical effectiveness and technical feasibility of this therap y modality could clearly be demonstrated in our study. To evaluate the clin ical relevance of the different beam modalities studies with larger patient numbers are necessary. To continue our project a new heavy ion accelerator exclusively fur clinical use is planned to be constructed in Heidelberg.