Sometimes, having one disease increases your risk for developing another disease. Patients who have inflammatory bowel disease, for example, are at higher risk for developing colorectal cancer. There’s also some concern that non-melanoma skin cancer may raise the risk of colorectal cancer, although that link is less clearly understood.
Here’s what we know about the link between these two diseases and CRC:
[See: 8 Questions to Ask Your Doctor About Colon Cancer.]
Inflammatory Bowel Disease and Colorectal Cancer
IBD — which includes Crohn’s disease and ulcerative colitis — is characterized by chronic inflammation of the gastrointestinal tract. Crohn’s disease can affect any organ in the GI tract, while ulcerative colitis primarily occurs in the colon and rectum. IBD is not the same as irritable bowel syndrome, although they’re commonly confused, says Dr. Darrell M. Gray II, a gastroenterologist with The Ohio State University Comprehensive Cancer Center — Arthur G. James Cancer Hospital and Richard J. Solove Research Institute. There’s no inflammation with IBS, Gray says, and it’s not associated with an increased risk for colorectal cancer.
“Chronic inflammation over time can increase your risk of colorectal cancer,” Gray says. The degree of risk depends on how long you’ve had IBD, how severe it is and how extensive your disease is; in other words, how much of the colon is involved. A family history of colorectal cancer — especially if the person was diagnosed before age 50 — also increases your risk for colorectal cancer if you have IBD.
The longer you’ve had IBD and the more severe your disease, the greater your risk of developing IBD-related colorectal cancer, Gray says. People who’ve had IBD for a long time have a 2.4 times greater risk of developing colorectal cancer than the general population, and they’re more likely to develop cancer at a younger age. Colorectal cancer accounts for 10 to 15 percent of deaths in IBD patients.
Colorectal cancers that develop in people with IBD don’t always follow the predictable transition from normal cells to abnormal cells to cancer. The abnormalities can also be more difficult to see. Whereas a typical polyp (an abnormal cell growth in the colon that has the potential to develop into cancer) tends to sit up off the surface of the colon wall (like a mushroom), IBD-related lesions are often flat and more challenging to remove completely. Furthermore, the molecular genetic changes that transform normal cells into cancer also tend to occur more rapidly in people with IBD than colorectal cancers that develop in the general population.
Surveillance is important in detecting and treating colorectal cancer in people with IBD, Gray says. “Once you’ve hit eight years of IBD, you should begin undergoing annual screening for colorectal cancer, regardless of your age.” Treating IBD with therapies that reduce inflammation can also help reduce your risk for colorectal cancer.
[See: 10 Seemingly Innocent Symptoms You Shouldn’t Ignore.]
Skin Cancer and Colorectal Cancer
Over the past 10 years, epidemiological studies, which analyze the pattern of diseases, have suggested there appears to be a link between non-melanoma skin cancer and an increased potential for a second primary cancer, says Dr. Tatiana Oberyszyn, a professor in the department of pathology at The Ohio State University Comprehensive Cancer Center. Oberyszyn, who is conducting her own research on the topic, says this association seems to hold true for a number of cancers, including prostate, breast, lung, salivary gland, mouth and colon. Skin cancers are categorized as melanoma or non-melanoma skin cancers. The primary types of non-melanoma skin cancer are squamous cell carcinoma and basal cell carcinoma.
Several studies have suggested an association between non-melanoma skin cancers and the development of a second primary cancer like colorectal cancer, Oberyszyn says. One study, published in 2014, which had a 50-year follow up and a large population, showed a strong correlation between previously having skin cancer and developing a second primary cancer, such as colorectal cancer, particularly if you were diagnosed with skin cancer at a young age.
Oberyszyn says that in the last several years, there’s been an increase in the number of cases of NMSC in patients younger than 40. At the same time, there’s also been an increase in colon cancer cases in the same age group. She says that while there’s no direct link yet between these increases, it suggests that there may be some cross talk between the two organs. And it’s also not just a one-off association. Oberyszyn points out that people with IBD or Crohn’s disease have associated skin problems.
Regardless of the underlying cause, Oberyszyn says there’s a strong suggestion that individuals can have up to a 130 percent risk of developing a secondary cancer after an initial squamous cell carcinoma. “If you do develop a secondary primary cancer and you had skin cancer, you could have an up to 25 percent increased risk of dying from that second primary cancer,” she says.
Oberyszyn says this increased risk of a second cancer in people who’ve had skin cancer could make sense. “We ignore the skin until there’s a problem,” she says. “The skin is the largest organ. It makes sense that if it’s damaged, things internally may change. If you’ve had a squamous cell carcinoma removed, you don’t think about having had cancer. Our mindset is, ‘The skin is not important. It was a small lesion.’ We need to think about it differently. You had cancer. You could be at risk of developing another primary cancer.”
[See: 7 Ways to Prevent Skin Cancer.]
Although there are currently no recommendations for earlier or more frequent colorectal cancer screening in people who’ve had skin cancer, Oberyszyn says that if you’ve developed skin cancer (especially if you were young), listen to your body and pay attention to any abnormal changes that might be a sign of colorectal cancer.
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