Blood and tissue biopsies are obtained by sigmoidoscopy or colonoscopy at baseline and at day 30 for correlative biomarker studies. The change in prostaglandin E_2 (PGE_2) is assessed by enzyme immunoassay, 5-hydroxy-eicosatetraenoic acid (5-HETE) by high-performance liquid chromatography, cyclooxygenases (COX-1 and COX-2) and 5-lipoxygenase (5-LOX) by western blotting, Ki-67 by immunohistochemistry, and glutathione peroxidase (GPx) by spectrophotometric assay.