Inflammatory bowel disease is associated with an increased risk of melanoma: a systematic review and meta-analysis

Background & aims: Inflammatory bowel disease (IBD) has been associated with an increased risk of nonmelanoma skin cancer, particularly among patients treated with thiopurines. It is unclear whether IBD affects risk for melanoma. We performed a systematic review and meta-analysis of cohort studies to determine the risk of melanoma in patients with IBD.

Methods: We conducted a systematic search of bibliographic databases through March 2013. Cohort studies reporting incident melanoma after IBD diagnosis and an estimate of incidence rate ratio or standardized incidence rate were included in the analysis. Pooled relative risk (RR) estimates with 95% confidence intervals (CIs) were calculated using the random-effects model.

Results: Our analysis included 12 studies, comprising a total of 172,837 patients with IBD; 179 cases of melanoma were reported from 1940 to 2009. The pooled crude incidence rate of melanoma in patients with IBD was 27.5 cases/100,000 person-years (95% CI, 19.9-37.0). Overall, IBD was associated with a 37% increase in risk of melanoma (12 studies: RR, 1.37; 95% CI, 1.10-1.70). The risk was increased among patients with Crohn's disease (7 studies: RR, 1.80; 95% CI, 1.17-2.75) and ulcerative colitis (7 studies: RR, 1.23; 95% CI, 1.01-1.50). The risk of melanoma was higher in studies performed before introduction of biologic therapies (before 1998) (8 studies: RR, 1.52; 95% CI, 1.02-2.25) but not in studies performed after 1998 (2 studies: RR, 1.08; 95% CI, 0.59-1.96).

Conclusions: Based on a meta-analysis, IBD has been associated with an increased risk of melanoma, independent of the use of biologic therapy. Patients diagnosed with IBD should be counseled on their risk for melanoma.