Crohn's Disease and Your Cancer Risk

Illustration of colon cancer

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As anyone with Crohn’s will admit, living with a chronic disease is a burden. The recurring pattern of feeling well, followed by painful flare-ups, can seem endless. With good medical care and some luck, the periods of good health will outweigh the flares.

So it does not seem right that some people with Crohn’s are at increased risk for cancer, but that is indeed the case. Even when bowel disease is well controlled or mild enough that surgery is unnecessary, cancer can make unwanted appearance years—even decades—after Crohn’s is diagnosed.

Fortunately, not all Crohn’s patients need to worry. The risk is only increased by certain characteristics of the disease and its treatments.

The Crohn’s-Colitis Connection

When Crohn's affects only the colon (the large intestine), it's called Crohn's granulomatous colitis. Often just known as Crohn's colitis, this form of Crohn's disease affects around 20% of people with Crohn's disease. Unlike ulcerative colitis, which causes inflammation only in the colon and rectum, Crohn’s disease can affect any part of the digestive tract from the mouth to the anus.

Patients with Crohn’s colitis—particularly younger patients—are at increased risk for colorectal cancer. This risk does not rise until seven or eight years after Crohn’s colitis is diagnosed. It tends to be more insidious in its onset than other colon cancers, often causing no symptoms until it is advanced. For this reason, patients with Crohn’s colitis must be kept under close surveillance even if they are doing well.

Until recently, colonoscopies with random biopsies were the gold standard for cancer surveillance. The system was not ideal, however, because random biopsies can miss cancerous or precancerous lesions. Today, a more advanced method called chromoendoscopy is available. It involves instilling a methylene blue dye into the gastrointestinal tract during colonoscopy. The dye is absorbed by the areas of dysplasia, which can be composed of premalignant cells. This makes it easy to see through an endoscope.

Crohn’s of the Small Intestine

The onset of cancer in a patient with Crohn’s of the small intestine, also known as small bowel Crohn's, is a rare complication. Unfortunately, it is impossible to surveil these patients, because the small bowel is difficult to access.

Most patients with small bowel Crohn’s who develop cancer are individuals whose disease has been stable for years before they suddenly develop a bowel obstruction, abdominal distention, or diarrhea. At this point, an imaging test such as a CT scan is used to look for an intestinal mass.

Rectal Stump Cancer

When the colon is removed, and the patient is given an ileostomy, the rectum may be totally or partially preserved. This allows the bowel to be reconnected at a future date. Many patients feel so much better with an ileostomy that they postpone restoration or abandon the idea.

However, the rectal stump can develop cancer and should be carefully watched with surveillance endoscopy. In general, the stump should be removed if patients are happy with their ileostomy and can tolerate surgery. This lowers their risk of developing cancer.

Fistulas and Abscesses

Perianal fistulas and abscesses resulting from longstanding Crohn’s disease increase the risk of developing squamous cell carcinoma (a form of skin cancer) or adenocarcinoma, the form of colon cancer mentioned above.

Cancer can develop at the site of an indwelling fistula or another chronic wound. Interestingly, it usually takes three or more decades for such cancers to develop. At this point, the patient can present with pain, bleeding, or a palpable perianal lump and a biopsy usually confirm the presence of cancer.

Cancer Risk From Treatment

A class of drugs known as biologic agents has revolutionized the treatment of Crohn’s disease. For many, biologics provide lasting relief they have not been able to obtain with conventional medication.

The downside to biologics is the small, but not insignificant, risk of developing lymphoma. This risk does not mean biologics should not be used: It does mean the risk should be discussed and considered before making a decision to proceed with one.

If you develop lymphoma while taking a biologic, the drug will be stopped. After the lymphoma has been treated, you and your doctor can discuss how best to control your Crohn’s. In some cases of intestinal lymphoma, surgery can be the best treatment option.

A Word From Verywell

If you have Crohn’s disease, work as a team with your doctor to keep your disease under control. This will mean creating a schedule for colonoscopies and sticking with it, even if you remain healthy for long periods of time.

Don’t forget that many Crohn’s-related cancers tend to develop after years—even decades—have passed. By allowing your doctor to surveil your digestive tract, even when your symptoms are under control, you help ensure that any cancer will be discovered in its early stage when the likelihood of cure is high.

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Article Sources

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