Colorectal cancer is associated with chronic inflammatory bowel disease

Inflammatory bowel disease includes ulcerative colitis and Crohn's disease, both of which involve chronic inflammation of the intestines and increase the risk of colorectal cancer.

1. Ulcerative colitis

Due to long-term chronic inflammation, the intestinal mucosa becomes congested, edematous and ulcerated. Stimulated by certain carcinogens, it may produce chronic granulomas or polyps and worsen to form colorectal cancer.

Among inflammatory bowel diseases, ulcerative colitis is most closely associated with colorectal cancer, with the risk of colorectal cancer being 5 to 11 times higher than that of people of the same age group. Colorectal cancer is rare in patients within 8 to 10 years, but the risk of developing a tumor increases by 0.5% to 10% each year thereafter.

It is recommended that patients with ulcerative colitis be monitored for dysplasia and cancer by colonoscopy. Patients with ulcerative colitis have an increased risk of small intestinal adenocarcinoma, but there is no suitable method to monitor this. In practice, this is not recommended.

2. Pancolitis

The incidence of colorectal cancer in patients with pancolitis is 2% for those with a disease duration of 10 years, 8% for those with a disease duration of 20 years, and 18% for those with a disease duration of more than 30 years.

3. Crohn's disease

The risk of malignant transformation of Crohn's disease is lower than that of ulcerative colitis, and its deterioration rate is 4 times higher than that of the same age control group. If the lesion occurs in the colon, the risk of colorectal disease in patients with Crohn's disease and ulcerative colitis is similar, so the colonoscopy monitoring program is the same as that for ulcerative colitis. Colonoscopy monitoring cannot reduce the risk of tumors in patients, but it can detect asymptomatic tumors and precancerous lesions early.