FACTORS INFLUENCING THE DEVELOPMENT OF SIGMOID COLON-CANCER - BACTERIOLOGICAL AND BIOCHEMICAL-STUDIES

BACKGROUND. Cancer of the sigmoid colon is especially sensitive to env ironmental factors such as food. The authors have conducted a series o f studies with food as the external environmental factor and intestina l microflora as the internal environmental factor in relation to sigmo id colon carcinogenesis. METHODS. Thirteen males who had previously un dergone surgery for sigmoid colon cancer, and who later developed new epithelial neoplasia of tile colon, were chosen as the high risk (HR) group. Fourteen males of similar age, whose large bowel was entirely n ormal by total colonoscopy, were chosen as the control (CONT) group. F ood constituents were analyzed by a dietician. Fecal bile acids, chole sterol metabolites, degradation products of amino acids, pH, water con tent, and bacterial flora were quantitatively analyzed. RESULTS. Altho ugh the HR group consumed slightly more carbon hydrate, fiber, and cal cium, as a whole, there was no significant difference in food constitu ents, especially animal fat, between the two groups. Concentrations of bile acids and cholesterol metabolites were not different between the groups, with the exception of a higher level of cholestanol in the HR group. Succinic, lactic, propionic, and isovaleric acids were abundan t in the HR group. Fecal pH and amounts of hydrogen sulfide and cresol also were higher in the HR group. The total amount of bacteria, lecit hinase-negative Clostridia, and Lactobacillus, were also more abundant in the HR group. CONCLUSIONS. The feces of the HR group was abundant in such substances as sigmoid colon cancer promoters, and appeared unr elated to food constituents. Resident flora of the HR group were abund ant in enzymatically active anaerobes. Because agents carcinogenic to the colon and rectum exist ubiquitously, microflora play a key role in sigmoid colon carcinogenesis by producing promoters. (C) 1996 America n Cancer Society.