The central hypothesis for this study is that it is safe and feasible to administer intraluminal photodynamic therapy (PDT) to colon cancers by colonoscopy to induce localized inflammatory/immune response. The objective is to demonstrate the feasibility and safety of PDT to colon cancer patients administered before surgery and to characterize the inflammatory/immune response at the tumor site and systemically. The long-term objective of these studies is to modify he natural biology of colorectal cancers and improve patient survival.