 Radiation Phase: Radiation therapy should begin within 30 days of definitive surgery or radiographic diagnosis, whichever is the later date. Date of surgery or radiographic diagnosis is considered day 1, and radiation should start no later than day 31. VPA will be continued daily without interruption during radiation therapy. VPA doses will be adjusted in increments of 5 mgkgday every 3-5 days to achieve and maintain trough concentrations between 85 to 115 mcgml. During this time patients will receive standard radiation therapy. 