ABSTRACT
This chapter examines whether the inhibitory effect is exerted directly on the intestinal epithelium or indirectly, by changing the luminal concentrations of free fatty acids and free bile acids. It shows that rectal cell proliferation, assessed by the stathmokinetic technique of metaphase arrest, is rapid than normal in patients with both active and quiescent ulcerative proctocolitis. The chapter presents a randomized prospective controlled trial of calcium supplements or placebo in patients with familial polyposis coli, who have undergone abdominal colectomy with ileorectal anastomosis, and who attend regularly for fulgeration of rectal adenomas. Conditions associated with an increased epithelial cell proliferation are also associated with a higher incidence of colorectal neoplasia. Cytokinetic data can be obtained in humans without the ethical constraints associated with administration of metaphase-arrest agents or radioisotopes. The finding that tumor incidence after a chemical carcinogen is reduced by calcium supplementation adds weight to the suggestion that the adaptation-carcinogenesis sequence is important in the etiology of gastrointestinal neoplasia.
