Preoperative Valproic Acid and Radiation Therapy for Rectal Cancer (V-shoRT-R3)

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.