Risk of melanoma and nonmelanoma skin cancer among patients with inflammatory bowel disease.

BACKGROUND & AIMS: Patients with inflammatory bowel disease (IBD) are at risk for certain malignancies. We aimed to determine the risk of melanoma and nonmelanoma skin cancer (NMSC) in patients with IBD and how medications affect these risks.

METHODS: We performed retrospective cohort and nested case-control studies using administrative data from the LifeLink Health Plan Claims Database from 1997 to 2009. The cohort comprised 108,579 patients with IBD, and each was matched to 4 individuals without IBD. The risk of melanoma and NMSC was evaluated by incidence rate ratio (IRR) and by adjusted Cox proportional hazard ratio (HR) modeling. In nested case-control studies, patients with melanoma or NMSC were matched to 4 patients with IBD without melanoma or NMSC. Conditional logistic regression was used to determine associations between medications and both skin cancers.

RESULTS: In the cohort, IBD was associated with an increased incidence of melanoma (IRR, 1.29; 95% confidence interval [CI], 1.09-1.53). Risk was greatest among individuals with Crohn's disease (IRR, 1.45; 95% CI, 1.13-1.85; adjusted HR, 1.28; 95% CI, 1.00-1.64). The incidence of NMSC also increased among patients with IBD (IRR, 1.46; 95% CI, 1.40-1.53) and was greatest among those with CD (IRR, 1.64; 95% CI, 1.54-1.74). In the nested case-control studies, therapy with biologics increased the risk of melanoma (odds ratio [OR], 1.88; 95% CI, 1.08-3.29). Patients who had been treated with thiopurines had an increased risk of NMSC (OR, 1.85; 95% CI, 1.66-2.05).

CONCLUSIONS: Immunosuppression increases the risk of melanoma and NMSC among patients with IBD. The risk of melanoma is increased by use of biologics, and the risk of NMSC is increased by use of thiopurines. Patients with IBD should be counseled and monitored for skin cancer.