Purpose: Known risk factors for the development of colorectal dysplasia or cancer in ulcerative colitis are total colonic involvement and long duration of the disease. It has recently been suggested that presence of primary sclerosing cholangitis is another independent risk factor-especially for proximal colorectal dysplasia or cancer-and that treatment with sulfasalazine might reduce the frequency of colorectal cancer in ulcerative colitis; the present study was undertaken to shed light on the validity of these theories.
Methods: A total of 143 patients with ulcerative colitis underwent regular colonoscopies and multiple biopsies in a 20-year surveillance program for studies of long-standing total ulcerative colitis. Fifty-one of the patients developed colorectal dysplasia or cancer. Patient records were scrutinized retrospectively for information of presence of primary sclerosing cholangitis, site of the colorectal malignancy, and results of sulfasalazine treatment.
Results: Nineteen of the patients had primary sclerosing cholangitis; these ran a significantly higher risk of developing colorectal dysplasia or cancer than patients with ulcerative colitis only. All colorectal cancers (n = 3) and 75 percent of all colorectal dysplasias or cancers among patients with primary sclerosing cholangitis were located in the proximal part of the colon, whereas 36 percent were found in that same region among the patients with ulcerative colitis without primary sclerosing cholangitis (P = 0.02). Sulfasalazine treatment showed no significant protective effect on the development of colorectal dysplasia or cancer in patients with ulcerative colitis.
Conclusion: The risk evaluation, as assessed by multivariate analysis, shows that primary sclerosing cholangitis proves to be an additional and independent risk factor for the development of colorectal dysplasia or cancer in patients with ulcerative colitis-particularly in the proximal part of the colon. The findings do not support the theory that sulfasalazine treatment exerts a protective effect against colorectal dysplasia or cancer.