Combination of photon and proton radiation therapy for chordomas and chondrosarcomas of the skull base: The Centre de Protontherapie d'Orsay experience

Purpose: Prospective analysis of local tumor control, survival, and treatme nt complications in 44 consecutive patients, treated with fractionated phot on and proton radiation for a chordoma or chondrosarcoma of the skull base. Methods and Materials : Between December 1995 and December 1998, 45 patient s with a median age of 55 years (14-85) were treated using a 201-MeV proton beam at the Centre de Protontherapie d'Orsay. 34 for a chordoma and 11 for a chondrosarcoma. Irradiation combined high-energy photons and protons. Ph otons represented two-thirds of the total dose and protons one-third. The m edian total dose delivered within the gross tumor volume was 67 cobalt Gray equivalent (CGE) (range: 60-70). Results: With a mean follow-up of 30.5 months (range: 2-56), the 3-year loc al control rates for chordomas and chondrosarcomas were 83.1% and 90%, resp ectively, and 3-year overall survival rates were 91% and 90%, respectively. Eight patients (18%) failed locally (7 within the clinical tumor volume an d 1 unknown). Four patients died of tumor and 2 others of intercurrent dise ase. In univariate analysis, young age at time of radiotherapy influenced l ocal control positively (p < 0.03), but not in multivariate analysis. Only 2 patients presented Grade 3 or 4 complications. Conclusion: In skull-base chordomas and chondrosarcomas, the combination of photons with a proton boost of one-third the total dose offers an excellen t chance of cure at the price of an acceptable toxicity. These results shou ld be confirmed with a longer follow-up. (C) 2001 Elsevier Science Inc.