The College of American Pathologists Conference XXVI in June 1994 was devoted to a discussion of the clinical relevance of prognostic factors in three solid tumors (breast, prostate, and colorectal). The group considering prognostic factors for adenocarcinoma of the large gut consisted of 15 pathologists, investigators, and surgeons. The group concluded that only a few items are well supported in the existing literature and can be recommended for routine clinical use at this time (pathologic TNM information and stage, tumor type, tumor grade, extramural venous invasion, and preoperative serum carcinoembryonic antigen level). According to the classification system used at the conference, these markers warrant categorization as important prognostic factors (category I). A few factors should be considered as potentially useful after further study (category II). Furthermore, the group agreed that all other current measurements of so-called prognostic factors do not warrant the same recognition of importance, either because they have been studied insufficiently or studies have demonstrated that they do not contribute to prognostication. These additional items were placed in category III. It was also concluded that the statistical methods used to identify and validate prognostic markers, as well as their integration into single statements of prognosis need further national evaluation and standardization.