Like Dennis Rodman and Madonna, it’s a relationship that seems unlikely. But findings from a new U.S. retrospective cohort study indicate that patients with Inflammatory Bowel Disease (IBD), especially those receiving the thiopurine class of medications to treat IBD, may be at risk for developing non-melanoma skin cancer (NMSC).
Dr. Millie Long of the University of North Carolina, Chapel Hill, and her colleagues investigated if IBD could be associated with a higher risk of non-melanoma skin cancer, and if the risk of that NMSC increased as a result of immunosuppressive and biologic medications.
IBD includes two related but different diseases: ulcerative colitis and Crohn's disease. These diseases cause chronic inflammation of the intestinal tract, which leads to a variety of symptoms and can also involve organs other than the intestines. IBD is a lifelong disease with periods of active disease alternating with periods of disease control (remission). IBD is sometimes confused with, but is different than irritable bowel syndrome.
According to the American College of Gastroenterology, there are more than one million people with IBD in the United States with new cases diagnosed at a rate of 10 cases per 100,000 people. These diseases account for 700,000 physician visits per year and 100,000 hospitalizations per year in the United States. Ulcerative colitis can be cured with surgery, but Crohn's disease is incurable.
When the patient records of 26,403 patients with Crohn's disease and 26,974 patients with ulcerative colitis, dating from 1996 through 2005 were matched by age, sex and region of the country with three randomly selected control patient records, the incidence rate ratios of non-melanoma skin cancer was higher (1.64) in patients with IBD compared to their matched controls. The researchers then set out to see if recent use of biologic or thiopurine class of immunosuppressive medications had any impact on non-melanoma skin cancer risk. Using a nested case-control study, 387 patients with Crohn's disease and NMSC and 355 patients with ulcerative colitis and NMSC were matched on age, sex and region with four random control patients with Crohn's disease or ulcerative colitis who did not have NMSC.
The researchers discovered recent use of any immunosuppressive medication within the last three months was associated with greater risk of NMSC as was recent use of the thiopurine class of immunosuppressive medications and recent use of biologic medications in patients with Crohn's disease.
Persistent use of any immunosuppressive medication, which was considered use for more than one year, was strongly associated with non-melanoma skin cancer (adjusted odds ratio 4.04), the study authors noted. The association was even stronger with persistent use of thiopurine medications (adjusted odds ratio 4.27). In Crohn's disease, persistent use of biologic medications was also associated with a raised risk (adjusted odds ratio 2.18).
“The increased risk of NMSC in patients with IBD is likely related to the immunosuppressive medications used to treat the disease, although we can't rule out changes to the immune system itself as a result of IBD as contributing to this risk,” explains Dr. Long who led the study. “In patients on immunosuppression therapy after organ transplant, previous studies have shown a clear association with NMSC. Other studies have demonstrated the drug, Azathioprine, [which is used for autoimmune diseases and is in the thiopurine class of immunosuppressive drugs,] can increase the photosensitization of human skin.”
Long concluded that the study “demonstrates that patients with IBD on immunosupression may also be at risk for non-melanoma skin cancer. As a result, [healthcare providers considering] long term management plans for IBD patients should stress the daily use of broad-spectrum sunscreen and increased awareness of non-melanoma skin cancer to help to prevent complications.”
The findings were presented at the American College of Gastroenterology's 74th Annual Scientific meeting in San Diego.
More information:The American Academy of Family Physicians has more about inflammatory bowel disease. The American Cancer Society has more information on non-melanoma skin cancer.
(SOURCE: American College of Gastroenterology, news release, Oct. 26, 2009)