Blood and urine samples are collected at baseline and on the day of surgery for tocopherol and biomarker analysis. A sample of colon tissue is removed during standard surgical resection for chemical analysis. Plasma, tumor tissue, and nontumorous tissues are analyzed for levels of F_2-isoprostane, 8-OHdG, 3-nitrotyrosine, and prostaglandin E_2 via enzyme immunoassays and for levels of α-, γ-, and δ-tocopherols via HPLC.