[Risk of cancer in chronic inflammatory bowel diseases].

This article summarizes the data concerning cancer risk in chronic inflammatory bowel disease. Cancer risk of ulcerative colitis and Crohn's disease is highly dependent on the duration of the disease, extent of bowel inflammation, and probably also of the age at onset of the disease. Cancer development follows the dysplasia-carcinoma-sequence. Diagnosis of premalignant changes is the basis for follow-up studies in ulcerative colitis as suggested here.