Highly conformal therapy using proton component in the management of meningiomas. Preliminary experience of the Centre de Protonthérapie d'Orsay.

Aims: To evaluate the efficacy and the tolerance of an escalated dose of external conformal fractionated radiation therapy combining photons and protons in the treatment of intracranial meningiomas.

Patients And Methods: Between December 1995 and December 1999, 17 patients received a treatment by 201-MeV proton beam at the Centre de Protonthérapie d'Orsay (CPO) for a meningioma. Five patients presented a histologically atypical or malignant meningioma, twelve patients a benign one that was recurrent or rapidly progressive. In two cases radiotherapy was administered in the initial course of the disease and in 15 cases at the time of relapse. A highly conformal approach was used combining high-energy photons and protons for approximately 2/3 and 1/3 of the total dose. The median total dose delivered within gross tumor volume was 61 Cobalt Gray Equivalent CGE (25-69).

Results: Median follow-up was 37 months (17-60). The 4-year local control and overall survival rates were 87.5 +/- 12% and 88.9 +/- 11%, respectively. One patient failed locally within the clinical tumor volume. One patient died of intercurrent disease. A complete or partial clinical improvement was seen in most of patients. Radiologically, there were eleven stable diseases and five partial responses. In 12/15 recurrent cases, the free interval after radiotherapy is longer than that achieved by the initial surgery. This radiotherapy was well tolerated.

Conclusions: In both benign and more aggressive meningiomas, the combination of conformal photons and protons with a dose escalated by 10-15% offers clinical improvements in most patients as well as radiological long-term stabilization.