Colorectal Cancer Association of Canada - CCAC

Just the Facts > Ulcerative Colitis and CRC  

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Colorectal Cancer & Inflammatory Bowel Disease


While the causes of colorectal cancer are still generally unknown, many risk factors have been identified outlining certain people who may be more susceptible in developing colorectal cancer. Risk factors include any underlying cause that could increase the risk of a person developing colorectal cancer. Among these groups, a strong connection has been established between Inflammatory Bowel Diseases, such as ulcerative colitis and Crohn’s disease, and the future development of colorectal cancer. There is no debate that ulcerative colitis bears a high risk for the development of colorectal cancer. (7) In Canada, there are approximately 65,000 people living with ulcerative colitis, with another 400 new cases diagnosed each year. The development of colorectal cancer accounts for one-third of deaths of these patients. (7) Additionally, the number of cases described has increased dramatically over the last decade. (3) There are now over 100 patients with colorectal cancer in association with ulcerative colitis, Crohn’s disease, ileocolitis or regional enteritis. (3)


Colorectal cancer has been known to affect those aged 50 years and older but is not restricted to that age bracket. (10) All adults should undergo colorectal cancer screening by age 50. (10) Most people with CRC have no symptoms until the cancer has grown and bowel symptoms begin. Screening tests can help identify cancers at an early and potentially treatable stage. (10) Some tests can also prevent the development of CRC by identifying precancerous abnormal growths called polyps, which can be removed before they become malignant.

Since the risk of Colorectal cancer in patients with ulcerative colitis grows with the duration and extent of disease, screening is necessary. (5) Studies have suggested that patients who are diagnosed with ulcerative colitis in childhood have a higher risk of cancer than those who are diagnosed later in life. In general, the prevalence of colorectal cancer in patients with ulcerative colitis is initially approximately 3.7 per cent. The risk for colorectal cancer increases with duration of disease; there was a 2 per cent incidence of cancer after 10 years, a 9 per cent incidence after 20 years, and a 19 per cent incidence after 30 years of disease. (7)

The reasons for this increased risk are quite simple. A prolonged period of inflammation anywhere in the body is not healthy. People with ulcerative colitis, as a result of their disease, often experience periods of inflammation specifically in their large intestine that may become more serious if not treated. Inflammation that exists in the large bowel, over a long period of time, leads to this higher risk.

Although it is generally accepted that the risk of colorectal cancer in patients with ulcerative colitis is increased compared with the general population, the management of this increased risk remains important. (5) Patients with ulcerative colitis typically undergo a colonoscopy every one to three years. (2) During these procedures, biopsy samples are taken every 10 cm along the length of the colon; if any of these samples reveals an abnormality, surgery to remove the rectum and some or the entire colon is considered.

As is the case with most cancers, the earlier the tumor is detected, the higher the chances of survival.

If you are a person living with ulcerative colitis, be sure to discuss your individual risk of developing colorectal cancer with your gastroenterologist. Together you can decide on the best screening test for you. It is critical that we all recognize the importance of screening for CRC. Early detection saves lives.


As you have read, patients with chronic ulcerative colitis have an elevated risk of developing CRC that rises with increased duration and extent of disease. (1) Given that ulcerative colitis is a chronic condition, nobody can control the duration of their disease. However, there are preventative methods to ensure a person can control the extent of their disease.

In a chronic, life-long disease such as ulcerative colitis, complex therapy regimens make it difficult for a patient to strictly adhere to therapy, often leading to non-compliance, or not taking medication as prescribed. Studies suggest the more pills a patient has to take or the higher the dosing frequency (the number of times a day a patient needs to take their medication), the less likely they are to strictly adhere to the regimen. Two North American Internet surveys (11) conducted with 451 ulcerative colitis patients and 300 gastroenterologists outlined this difficulty of adherence with UC medication. Both patients and gastroenterologists reported that managing UC medication is a struggle for patients (49 per cent and 41 per cent respectively) and that it is difficult for patients to take medication as prescribed every day (42 per cent and 90 per cent respectively). This difficulty was further exemplified by the fact that 46 per cent of patients reported not taking all of their medication in the past week (11).

Essentially, the increased inflammation is a result of a downward spiral. The more complicated a therapy regimen is, the less likely a patient is to take the medication as it was prescribed by their gastroenterologist. The less adherent a patient is, the less likely the medication they are taking will work as it is intended to. The less a medication works, the higher the probability exists of more inflammation in the colon, leading to a higher risk of developing colorectal cancer.

Stopping this downward spiral is simple – it is paramount to take medication as prescribed by a doctor, or adhere to the therapy regimen. If a patient adheres to their medication, the likelihood of reducing any inflammation in their colon increases. Please note, the results of every medication, even when taken as intended, vary from person to person.

If you find you are having difficulty adhering to the therapy regimen prescribed by your doctor, speak to your gastroenterologist about finding a medication that suits your lifestyle, or a medication that is simpler for you to take.

Ultimately, the easier a medication is for you to remember, the more you are likely to take it properly.

Preventative Mechanism

Cancer prevention is an action taken to lower the chance of getting cancer. (9) By preventing cancer, the number of new cases of cancer in a group or population is lowered. (9) Hopefully, this will lower the number of deaths caused by cancer. (9) To prevent new cancers from starting, scientists look at risk factors and protective factors. (9) Anything that increases your chance of developing cancer is called a cancer risk factor; anything that decreases your chance of developing cancer is called a cancer protective factor. (9) Some examples of protective factors for colorectal cancer, in addition to medication adherence, are getting regular physical activity, staying at a healthy weight and having a healthy diet. (9) These lifestyle choices encourage healthy living. Possible prevention methods include quitting smoking, reducing drinking to a moderate level and continuous screening. (9)

Regular use of 5-ASA therapy has also been shown to prevent the onset of colorectal cancer. A recent analysis of nine different studies involving 1,932 ulcerative colitis patients showed a 49 per cent reduction in risk of developing colorectal cancer in patients taking 5-ASA regularly (12). In addition to the fact that regular 5-ASA use prevents long periods of inflammation in the colon, it is believed that 5-ASA therapy also interferes in several aspects of cancer development thus increasing its protective ability against colorectal cancer (12). Avoiding risk factors and increasing protective factors may lower your risk, but it does not mean that you will not get cancer. (9)

(1)Lashner BA. Recommendations for colorectal cancer screening in ulcerative colitis: A review of research from a single university-based surveillance program. Am J Gastroenterol 1992; 87:168-175.

(2) (3) Greenstein A, Sachar D, Pucillo A, et al. Cancer in universal and left sided ulcerative colitis: Clinical and pathologic features. Mt Sinai J Med 1981; 46:25-32. (4) Gyde SN, Prior P, Allan RN, et al. Colorectal cancer in ulcerative colitis: A cohort study of primary referrals from three centres. Gut 1988; 29:206-217. (5) Lashner BA, Hanauer SB, Silverstein MD. Optimal timing of colonoscopy to screen for cancer in ulcerative colitis. Ann Intern Med 1988; 108:274-278. (6) Ekbom A, Helmick C, Zack M, et al. Ulcerative colitis and colorectal cancer. A population-based study. N Engl J Med 1990; 323:1228-1233. (7) (8)Marchesa P, Lashner BA, Lavery IC, et al. The risk of cancer and dysplasia among ulcerative colitis patients with primary sclerosing cholangitis. Am J Gastroenterol 1997; 92:1285-1288. (9)

(10) Young, T,J Gen Intern Med. Early Detection is critical HOUSE CALLS, The Nor’wester. Published online April 10, 2010.

(11) Rubin, David T., et al. Patient and physician perceptions on living with ulcerative colitis: results from two Internet surveys. Abstract presented at the American College of Gastroenterology, Philadelphia, PA, Oct, 2007.

(12) Rubin, David T., et al. Colorectal Cancer Prevention in Inflammatory Bowel Disease and the Role of 5-Aminosalicylic Acid: a Clinical Review and Update. Inflammatory Bowel Disease, Feb 2008; Vol.14:265–274.