Review of skull base chordomas: prognostic factors and long-term results of proton-beam radiotherapy.

Fractionated proton beam radiotherapy has been used for skull base tumors in the United States since the mid-70s, and more than 300 patients in whom diagnosis of chordoma of the skull base has been made have been treated. The ability to achieve high degrees of radiation dose conformity by using protons has resulted in higher radiation doses than can be delivered with conventional radiotherapy in the base of skull. High target volume doses have led to improved tumor control and patient survival. Side effects such as severe toxicity are acceptable considering the alternatives of uncontrolled tumor growth. The authors of various analyses have identified prognostic factors that can be used to predict a patient's chance of treatment success. On the horizon are important technical developments that will further increase dose conformity and increase target doses. In this paper the author reviews long-term outcome data and prognostic predictors for survival of patients with skull base chordomas based on the largest worldwide patient series.