Preoperative Valproic Acid and Radiation Therapy for Rectal Cancer

The purpose of this study is to first determine the maximum tolerated dose of capecitabine given alone or in combination with valproic acid during preoperative short-course radiotherapy (Phase 1). The next part of the study (Phase 2)will explore whether the addition of valproic acid or the addition of capecitabine to short-course radiotherapy, before optimal radical surgery might increase the pathologic complete tumor regression rate in patients with low-moderate risk rectal cancer.