Ulcerative colitis: sclerosing cholangitis today, cancer tomorrow?

The relation between inflammatory bowel disease (IBD), mainly ulcerative colitis, and primary sclerosing cholangitis (PSC) is particularly close, as approximately two thirds of patients with PSC have, or will develop, ulcerative colitis, and PSC occurs in approximately 3–7% of patients with ulcerative colitis. In a large Swedish epidemiological study, approximately 5.5% of patients with extensive colitis had PSC. 1 Despite the close relation the aetiology of both diseases is unknown. It is well established that patients with ulcerative colitis have an increased risk of developing colorectal carcinoma. The two major risk factors that have been identified in the development of neoplasia are duration of disease and the extent of colitis. Additional risk factors have been described such as the presence of colonic epithelial cell dysplasia and early onset of colitis. It has been suggested that pharmacological treatment for ulcerative colitis may reduce the risk of colorectal cancer. 2 Recently, the presence of PSC has been suggested to increase the risk of dysplasia and colorectal cancer in patients with ulcerative colitis. 3 In the initial reports from Sweden the absolute cumulative risk of developing colorectal dysplasia/carcinoma in the PSC/ulcerative colitis group was 9%, 31% and 50%, respectively after 10, 20 and 25 years of disease duration. In the group with ulcerative colitis only, the corresponding risk was 2%, 5% and 10%, respectively. 3 Moreover, 10 of the patients with PSC developed cholangiocarcinoma, all but one having ulcerative colitis, whereas in the control group of patients with ulcerative colitis, no cholangiocarcinoma occurred. This suggests that patients with PSC have an increased neoplas-tic potential to develop cholangiocarcinoma and colon cancer. These findings have been confirmed by a number of other studies from North America. 4 5 However, conflicting data were provided by the Mayo Clinic. 6 Loftus et al pointed out that previous studies have been limited by small sample size and the possibility of referral bias. They identified 178 patients with PSC who were stratified by geographical area of residence and were followed up to determine survival and development of colorectal cancer. 6 As expected, the relative risk of colorectal cancer was increased 10-fold in those patients who had PSC and ulcerative colitis, but there was no increased risk in patients who had PSC alone. 6 The number of cancers observed was similar to those expected in patients with ulcerative colitis. The problems with assessing the risk of PSC in ulcerative colitis …