CANCERS IN IBD
Risk L 7
The cancer rate is high in the United States for everyone over their lifetime with a small increase risk for those with Crohn's disease and a larger one for those with ulcerative colitis.
If we take Non-Hodgkin's Lymphoma, the most common cancer associated with Crohn's disease and its treatment, a group of doctors reviewed the 26 different articles that record 13 lymphomas in 8905 adult patients (that's 1.5 in every 1000 patients) over the average 2 1/2 years they were studied, with certain biologic medicines (Remicade, Humira and Cimzia) raising the risk compared to the rest of us in the general population, but as Dr. Siegel concludes, "the absolute rate of these events remains low and should be weighed against the substantial benefits associated with treatment." (PF Dulai and others, Clinical Gastroenterology and Hepatology, 2014, pages 1443-51)
Older patients (those over 65) have a higher risk whether or not they were on these medicines. Other studies have had similar conclusions or else showed that other drugs, azathioprine (Imuran) or 6-mercaptopurine (together, these are the thiopurine medications) had a higher rate of causing lymphoma than the newer biologics, but just a mildly higher rate. Additionally, studies are now showing that those who have repeated CT scans are at increased risk of developing cancer.
T Cell Lymphomas
The combination of biologics and thioprines used together increases the risk for developing a rare cancer called hepatosplenic T cell lymphoma (HSTCL), particularly in young males (teens through their 30s). But fortunately, we now recognize 3 facts, that HSTCL
- occurs most often in young males
- occurs when biologics are used along with thiopurines, but still at very low rates
- rarely occurs in the first 6 months when they are used together
Because we now know this, the combination is rarely used in young males for very long, even though the risk for this type of cancer is only 1 person in 1,000 even when these medicines are used together. And the risk is much lower than that in their first 6 months together–that seems to be particularly important because the anti-TNFs work faster and better in those first few months if they are used with the thiopurines.
The thioprines increase the risk of developing skin cancers by 3 to 4 times compared to the rest of the population. The increase with biologics is 2 to 3 times the rest of the population). When biologics and thiopurines are combined to improve their impact on Crohn's disease, the combination also increases the risk of skin cancers to 5 or 6 times compared to the risk for the rest of us. Fortunately, these usually can be removed with surgery.
Although as many as 5% of those with ulcerative colitis develop colon cancer during their lifetime, that also means that 95% of those with ulcerative colitis won't have colon cancer. For those with Crohn's disease, the risk of developing cancer is lower (about 1% of those with Crohn's in the large intestine). But those are averages—the odds for any particular patient changes is based on a number of factors:
- Disease control. Cancer generally comes in actively inflamed areas. If the disease is controlled, that reduces the risk dramatically.
- Amount of colitis. Those who just have colitis at the very bottom of the intestine (the rectum) have risks that are similar to those who don't have colitis. Those at greater risk are UCees (those with ulcerative colitis) throughout their entire colon (the large intestine).
- Length of time with IBD. The longer someone has IBD, and certainly the longer it is active, raises the risk of cancer.
- Those who also have liver disease (primary sclerosing cholangitis) are at higher risk for developing colon and liver cancers.
- Diet. Animal fats seem to increase the risk of developing colon cancer
So it's especially important for UCees to
- Make sure they are on a medicine that is keeping their disease under control.
- Stay on a healthy diet with lots of fruits, vegetables and fiber and limited in the amount of animal fat.
- Have yearly colonoscopy for cancer screening after they've had the disease for 8 years.
Those with Crohn's can get cancers in the colon too, if they have active disease there, though it seems to be less frequent than ones that come with ulcerative colitis. They can also get cancer in the lower intestine if they have had inflammation there for a long time (20 years is the length of time that's often quoted.
And both Crohn's disease and ulcerative colitis can be associated with a particular liver / bile duct cancer called cholangiocarcinoma, if they have a rare condition called primary sclerosing cholangitis.
- Cancer is common for all of us, and obviously, quite serious.
- Cancer risk is increased somewhat in inflammatory bowel diseases, and this may be further increased by having repeated CT scans.
- The risk of developing cancer may also be increased with certain medications and particularly when those medicines (thiopurines and biologics) are used together. However, that risk is still small and must be balanced by the benefits of the medicine, since keeping the intestine under control
- also seems to lessen the risk of developing cancer.
Many thanks to Sally Lorimer for helping to balance the risks of IBD against those in our everyday lives.
This article, as well as all others, was reviewed and edited by a member of our Medical Advisory Board.
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