Previous studies of gastric secretory function and serum gastrin levels in patients with chronic renal failure (CRF) have yielded conflicting results. In a study of 30 patients on regular hemodialysis, serum gastrin levels were higher than normal (p < 0.05), and the gastric secretory response to pentagastrin was normal for the group as a whole. There were, however, 8 patients who were hypochlorhydric (4 achlorhydric) and 7 who were hyperchlorhydric. The patients with gastric hyposecretion were older, predominantly male and this group was associated with the highest gastrin levels as well as the highest incidence of gastrointestinal hemorrhage. Chronic gastritis is thus more common in CRF than generally believed and may be responsible for much of the morbidity from gastrointestinal complications during hemodialysis.

Twenty (44%) of 45 patients with cutaneous pellagra had diarrhoea. Inflammation was seen on sigmoidoscopy in 42 and was severe in 5 (11%), moderate in 4 (9%) and mild in 33 (73%). Six patients (13%) had perianal excoriation. Rectal biopsies taken in all cases showed extensive ulceration in 1 case, moderate to severe inflammation in 16 (36%) and mild inflammation in 18 (40%). Minimal oedema of the lamina propria was seen in 11 (24%) patients. At 5 to 7 days after starting vitamin treatment in nine cases histological changes had returned to normal in 4, improved in 3 and had not changed in 2. Diarrhoea stopped within a week in all cases.

Colorectal cancer is the second most common cancer in many Western countries.' It is, however, uncommon in developing societies. The incidence in South African Blacks is one of the lowest in the world.2 Thus the mortality rate for the period 1968-71 was 0-8 per 100000 population. This is in striking contrast with the Johannesburg White population, with a mortality rate of 13 per 100000 population (Unpublished data). (Table 1).During a 12-year period 96 cases of large bowel cancer were diagnosed from an urban Black population of at least one million.3 During the same period, only six adenomatous polyps were observed as surgical specimens. Isaacson et al. (1978)2 confirmed the low occurrence, and, in addition, showed that no significant alteration in incidence had occurred over the past 20 years.The purpose of this study is (1) to examine some characteristics of colorectal cancer in Black and White patients treated at Baragwanath and the Johannesburg General Hospital, and (2) in particular to examine the relevance of the adenoma-carcinoma sequence in Black patients with carcinoma.