At-52 * prospective early results of low grade glioma patients treated with proton therapy

BACKGROUND: This is a prospective study to evaluate potential treatment toxicity and progression free survival (PFS) of low grade glioma patients treated with proton radiation therapy. METHODS: Twenty WHO grade II glioma patients indicated for radiation therapy (8 new high risk diagnoses; 12 recurrent/progressive disease) were enrolled on a prospective single arm trial of proton therapy receiving 54 Gy(RBE) in 30 fractions. Comprehensive baseline and regular post treatment evaluations of neurocognitive function, neuroendocrine function, and quality of life (QOL) were performed. RESULTS: All 20 patients (median age 37.5 years) tolerated treatment without difficulty. Median follow up after proton therapy was 5.1 years. Baseline level of intellectual functioning on a standardized IQ measure was within the normal range for the group and remained stable over time. Performances in the cognitive domains of visuospatial ability, language function, attention/working memory, and processing speed were also in the normal range at baseline and did not decline over time. New endocrine dysfunction was detected in six patients and all but one had direct irradiation of the hypothalamic-pituitary axis. QOL assessment showed no change over time with the extended follow up. PFS at 3 years was 85% and at 5 years was 40%. CONCLUSIONS: Low grade glioma patients tolerate proton therapy well and a subset develops neuroendocrine deficiencies. There was no evidence for decline in cognitive function or QOL which may be partially attributable to reduced radiation dose to the normal brain by use of proton therapy. PFS was similar to that of photon based therapy.