Patients With IBD at Risk of Developing Nonmelanoma Skin Cancer

Deborah Brauser

October 28, 2009

October 28, 2009 (San Diego, California) — Patients with inflammatory bowel disease (IBD) are more than 60% more likely to develop nonmelanoma skin cancer (NMSC) than their counterparts without IBD, according to the findings of a new retrospective cohort study presented here at the American College of Gastroenterology (ACG) 2009 Annual Scientific Meeting.

Dr. Millie Long

In addition, the persistent use of immunosuppressant medications in treating IBD, especially thiopurines, is strongly associated with an increased risk for NMSC, researchers reported.

Results of the study, which won the 2009 ACG/Centocor IBD Abstract Award, were presented during a podium session by lead investigator Millie Long, MD, from the University of North Carolina at Chapel Hill.

Evaluating IBD, Immunosuppressants, and Biologics

"One in 5 Americans develop skin cancer, which accounts for a third of all cancers in the United States," said Dr. Long during her presentation. She reported that although 2 previous studies have suggested that patients with IBD are at an increased risk for skin cancer related to immunosuppression, they did not look at specific medication use.

In this study, Dr. Long and colleagues sought to evaluate the risk for NMSC in patients with IBD and, secondarily, to determine whether immunosuppressive and biologic medications increase the risk for NMSC.

They examined the records of 26,403 patients with Crohn's disease (CD) and 26,974 with ulcerative colitis (UC) from the PharMetrics Patient-Centric Database from 1996 to 2005. Each patient was then matched by age, sex, and region of the country with 3 randomly selected control subjects without either CD or UC (n = 160,131). The mean age of the cohort was approximately 40 years.

Results showed that the annual NMSC incidence per 100,000 patients was higher in the overall IBD patients than in their matched controls (773 cases vs 447 cases; incidence rate ratio [IRR], 1.64; 95% confidence interval [CI], 1.51 - 1.78).

"In other words, those with IBD were over 60% more likely to develop [NMSC]," said Dr. Long.

She explained that this increase is likely related to the immunosuppressants used to treat the disease. However, "we can't rule out changes to the immune system itself, as a result of IBD, contributing to this risk."

In a second, nested case-control study examining medication use, 743 patients with NMSC and either CD (n = 387) or UC (n = 356) were each matched to 4 randomly selected control subjects with CD or UC and without NMSC.

Results of this examination showed that recent use (within 90 days) of any immunosuppressive medication was associated with an adjusted odds ratio (OR) of 3.28 (95% CI, 2.62 - 4.10) of NMSC development, whereas thiopurine use was associated with an adjusted OR of 3.56 (95% CI, 2.81 - 4.50).

In addition, persistent use (>365 days) of any immunosuppressant was strongly associated with NMSC development (adjusted OR, 4.04; 95% CI, 2.96 - 5.53), especially with persistent use of thiopurines (adjusted OR, 4.27; 95% CI, 3.08 - 5.92).

Recent and persistent use of any biologic among those with CD were also associated with NMSC (adjusted OR, 2.07; 95% CI, 1.28 - 3.33 and adjusted OR, 2.18; 95% CI, 1.07 - 4.46, respectively). However, Dr. Long said that patient numbers were underpowered to evaluate the effect of biologics on UC.

"Overall, we found that patients with IBD, especially those receiving the thiopurine class of medications, are at risk for NMSC," Dr. Long told Medscape Gastroenterology after her presentation. "We're now advocating for increased awareness of skin cancer risk by both IBD patients and providers."

However, when asked if she would now recommend screenings of all IBD patients for NMSC, Dr. Long replied: "I don't think we're quite there yet."

Benefits Still Outweigh the Risks

Dr. Eamonn Quigley

"I think this has to be regarded as a very important study because of the sheer number of patients involved and the quality of the methodology that was used," said Eamonn Quigley, MD, professor of medicine and human physiology at the National University of Ireland in Cork, and outgoing president of the ACG. Dr. Quigley was not involved with this study.

"These results are to be taken seriously but they also have to be put into perspective. While there was a definite increase in risk for skin cancer, the actual numbers were still fairly small," said Dr. Quigley.

He added: "We don't want to scare patients into thinking they shouldn't be taking this medication. For the vast majority, the benefits greatly outweigh the risks."

Dr. Quigley said that his take-away message from this study is that "we shouldn't be thinking of restricting the patient's drugs. Instead, we should be thinking of careful surveillance for the development of skin cancer and picking up early signs in these patients, particularly for those on immunomodulators."

"With IBD, when we're dealing with agents that are very effective but also complex and not without side effects, then we need to monitor them very carefully."

Dr. Long and Dr. Quigley have disclosed no relevant financial relationships.

American College of Gastroenterology (ACG) 2009 Annual Scientific Meeting: Abstract 6. Presented October 26, 2009.


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