Understanding ulcerative colitis: a risk factor for colorectal cancer

Ulcerative colitis is a chronic inflammatory bowel disease that affects the lining of the large intestine (colon and rectum). It causes inflammation and ulcers (sores) that result in the following signs and symptoms:

•Diarrhea, often with blood or pus

•Abdominal pain and cramping

•Rectal pain

•Rectal bleeding (passing small amounts of blood in the stool)

•Weight loss

•Fatigue

•Fever (in severe cases)

Ulcerative colitis develops when the immune system mistakenly attacks the cells of the lining of the colon as if they were foreign invaders, causing damage over time. While the exact cause is not known, potential causes include:

•Imbalances in the populations of good and bad bacteria in the gut microbiome

•Specific genetic inherited factors have been implicated in the development of the disease, where studies have shown that 1 in 4 individuals with ulcerative colitis have a family history of the condition

•Environmental factors such as medication use, pollution, and certain types of diets have been associated with the incidence of the disease. It appears to be more common in urban areas of northern parts of western Europe and America. [1]

Connection to colorectal cancer risk

Since ulcerative colitis is a chronic inflammatory condition that damages the lining of the colon over time, the inflammation and constant cell repair can result in a mutation that causes cancer. Cases of ulcerative colitis that are more severe or long-term are associated with a higher risk of developing colorectal cancer. Similarly, a higher risk of colorectal cancer is observed in people with Crohn’s disease; another form of chronic GI inflammation.

Reducing colorectal cancer risk

If you have been diagnosed with ulcerative colitis, it is recommended to begin screening by getting a colonoscopy every 1-2 years beginning at 8-10 years after onset of symptoms (not date of diagnosis). Furthermore, it is important to keep inflammation under control with medication, which range from anti-inflammatory drugs to drugs that suppress the activity of your immune system. The medication that you take will depend on the severity of the colitis.

If an individual undergoes two colonoscopies in a row with no evidence of damage, inflammation, polyps or abnormal cells in the colon, there are considered to be in remission. With new types of medication that are available today, remission is a possibility for some patients. For patients who do not respond to available medications, surgical removal of a part or all of the colon is an option. In the instance that the entire colon is removed, the patient would manage their stool through an internal or external storage pouch.

Colorectal cancer treatment and ulcerative colitis

Certain treatments for colorectal cancer, such as chemotherapy and immunotherapy, can cause irritation to mucosa including the intestinal mucosa (inner lining), resulting in digestive problems. If you are beginning treatment for colorectal cancer, it is important to notify your doctor of any chronic inflammatory bowel conditions so that they are under control before beginning treatment. This way, side effects from treatment can be minimized.

Immunotherapy-induced colitis

For patients undergoing treatment for colorectal cancer with immunotherapy agents, colitis is one of the immune-related side effects. About 45% of patients will develop colitis from immunotherapy treatment [2]. Best management of immunotherapy-induced colitis includes early recognition and timely use of immune-suppressing drugs to control symptoms.

Learn about the Risks Factors and Symptoms of Colorectal Cancer

There are other risk factors associated with the development of colorectal cancer.

Explore the Colorectal Cancer Canada website and become familiar with colorectal cancer risk factors, symptoms, and treatments.

[1] https://www.nhs.uk/conditions/ulcerative-colitis/causes/

[2] https://www.mdanderson.org/cancerwise/does-ulcerative-colitis-affect-your-colorectal-cancer-risk.h00-159462423.html#:~:text=The%20more%20extensive%20your%20colitis,greater%20risk%20for%20colorectal%20cancer.