[Radiation therapy for chordomas and chondrosarcomas of the base of the skull and cervical spine].

Purpose: Prospective analysis of local tumour control, survival and treatment complications in 67 consecutive patients treated with fractionated photon and proton radiation for a chordoma or a chondrosarcoma of the base of the skull and of the cervical spine.

Patients And Methods: Between December 1995 and January 2000, 67 patients with a median age of 52.3 years (14-85), were treated using 201 MeV proton beam of the centre de protonthérapie d'Orsay (CPO), 49 for a chordoma and 18 for a chondrosarcoma. Irradiation combined high-energy photons and protons. Photons represented 2/3 of the total dose and protons 1/3. The median total dose delivered within gross tumour volume was 67 Cobalt Gray Equivalent (CGE) (60-70).

Results: With a mean follow-up of 32 months (4-71), the 3-year local control rates were for chordomas and chondrosarcomas of 70.8% and 85.2%, respectively and 4-year overall survival rates of 87.7% and 75%, respectively. Fourteen tumours (21.5%) failed locally (eight within the gross tumor volume, four into the CTV and 2 in an unknown site). Seven patients died of tumour and one of intercurrent disease. In univariate analysis, age inférieur ou égal à 52.3 years (p = 0.002), maximum tumoral diameter < 44.7 mm (p = 0.02) and GTV < 28.4 mL (0.02), at time of radiotherapy, influenced positively the local control. According to multivariate analysis, only age was an independent prognostic factor of local control. Only five (7.7%) patients presented grade 3 or 4 complications.

Conclusion: In base of skull chordomas and chondrosarcomas, the combined photon and proton therapy offers excellent chances of cure at the price of an acceptable toxicity. These results should be confirmed with a longer follow-up.