Molecular underpinnings of cancer in ulcerative colitis.

Ulcerative colitis (UC) is a chronic inflammatory disease of the colon that can lead to cancer. Patients with UC have approximately 20% lifetime risk of colon cancer, with the risk increasing with the duration of disease. Why some patients develop colorectal cancer and others do not is not clearly understood. Evidence reveals that the UC patients who develop cancer have an underlying process of instability in the colonic mucosa as measured by DNA fingerprinting and fluorescent in situ hybridization techniques. The cause of instability may be shortened telomeres, the protective ends of chromosomes. Patients who progress to dysplasia and cancer have shorter telomeres, which become sticky and cause telomeric bridges to form, with subsequent chromosomal breakage. Thus, UC patients who have dysplasia and cancer appear to have a mutator phenotype present in the colonic mucosa that underlies the process of tumorigenesis.