CANCER RISKS IN IBD

Risk L6

Sally Lorimer, Stan Cohen

Any idea of what your risk is of developing cancer in your lifetime? Not someone with IBD, but anyone.   In the United States. It's 1 in every 2 males (half of all males) and 1 in 3 females (one third of all females). That's a 33-50% chance that each one of us will get cancer. And there's a 20-25% chance that cancer will kill us, according to the American Cancer Society. That has little or nothing to do with having IBD. That's life in the US, though it increases if you smoke or have certain genes, and of course, it varies by whether you are male (M) or female (F). Look at the table.

What this says is that there is a real risk of developing cancer sometime during our lives. That has nothing to do with having IBD. That's not intended to scare you. If you look at the table, you see that most of the people who get cancer survive. In the general population, there's actually a greater risk of dying from heart disease. 

Cancer in IBD

There are problems in comparing those statistics with the ones used to show the risks of medication in IBD. First, there is an increased risk of colon cancer with ulcerative colitis (UC), where the risk increases 1/2-1% every year after the first 8-10 years of having UC. And it may be 2-3 times that if most or all of the colon is involved with active disease.  Crohn's disease does not appear to have that same risk unless the entire colon is affected, and even then, the risk level appears to be lower in Crohn's disease. The second, is that it is hard to compare the lifetime risk in the table with people who are different ages when they develop IBD, require different medicines and need CT scans at times, since x-rays carry some risk. 

That doesn't mean we can't estimate the risks. We just can't compare cancer risks in those with IBD and cancer in everybody else in the same way.