I. To determine whether proton therapy, compared to intensity-modulated radiation therapy (IMRT), preserves cognitive outcomes over time as measured by the Clinical Trial Battery Composite (CTB COMP) score (calculated from the Hopkins Verbal Learning Test Revised [HVLT-R]) Total Recall, HVLT-R Delayed Recall, HVLT-R Delayed Recognition, Controlled Oral Word Association (COWA) test, Trail Making Test (TMT) part A and part B.