Morphology of Precancer in Colitis

There is general agreement that malignant change in ulcerative colitis mostly occurs in those patients whose large intestine is totally involved and have a history of symptoms for more than 10 years. Having thus defined the population of colitics most at risk the problem remains of identifying the individual patient destined to get carcinoma. There is yet no evidence that all the population at risk will eventually develop malignant change. It has been previously pointed out that some test is required which will decide that a patient with ulcerative colitis has entered a precancerous phase (Morson, 1966). The detection of epithelial changes suggestive of precancer or carcinoma in situ in rectal biopsies from patients with ulcerative colitis prompted an investigation into the incidence and extent of such changes in colectomy specimens removed for colitis with and without malignant change. The results of this enquiry are reported here as well as an analysis of the first nine patients in whom the diagnosis of precancer was made in a rectal biopsy and played an important part, together with clinical and radiological observations, in the subsequent decision to perform total proctocolectomy.