Proton therapy for skull base chordomas and chondrosarcomas

Abstract

Chordomas and chondrosarcomas of the base of the skull and cervical spine are vexing therapeutic problems because of their location and proximity to several critical structures. Recurrence after surgery alone is common; postoperative irradiation is an acknowledged part of the overall therapy plan. Tumor control rates improve with higher total doses, but these carry an increased risk of irreversible damage to the surrounding structures. Protons, because of their positive charge, which allows for more controllability than conventional X-rays, enable delivery of high total doses while sparing the nearby critical structures. This ability to deliver doses greater than 70. Gy has resulted in higher rates of disease control without increasing the toxicity. Control is improved if proton irradiation is given as adjuvant treatment, when the volume of tumor is smallest, rather than at recurrence. Our experience suggests that fractionated protons given following maximum surgical resection provide good local control with minimal toxicity.