Histochemical alterations of mucin in normal colon, inflammatory bowel disease and colonic adenocarcinoma

Loss of sialic acid o-acyl substitutions in colonic mucus was studied using specific histochemical techniques in individuals with a variety of large-bowel diseases and in a control population. Changes found included a focal or field (diffuse) loss of side-chain substitutions which were qualitatively similar in all groups studied. The results were tested statistically using a variety of assumptions that field and/or focal loss of o-acyl substitution may be either abnormal or a normal variant. No statistically significant differences in the prevalence of substitutions were detected between normal males and females or between normal individuals aged 0-29 years and 30-80 years. Significant differences were found between ascending and descending colon in both normal individuals and in the non-neoplastic mucosa of patients with cancer. There were also significant differences between the normal descending colon and cases with cancer of the descending colon. These differences seem unlikely to be due to non-specific factors, since for most assumptions there were also differences between colons containing cancer and those from patients with inflammatory bowel disease. In agreement with the work of other investigators, it seems likely that focal loss of o-acetylation results from an acquired gene mutation. It is not clear whether or not this plays a role in carcinogenesis.