BackgroundVarious immune-mediated diseases are associated with increased malignancy risks. However, the relationship between Behçet’s disease (BD) and cancer remains unclear. We conducted a nationwide, population-based study to determine the risk of cancer in patients with BD.MethodsUsing National Health Insurance claims records, we collected data from 2402 patients diagnosed with BD between 2013 and 2014. Standardized incidence ratios (SIRs) of overall and site-specific cancers in patients with BD in comparison with the general population were calculated.ResultsThe risks of overall cancer (SIR, 3.54; 95% confidence interval, 2.35–5.11 in men and 2.17; 1.58–2.92 in women) and solid cancer (3.10; 1.94–4.69 in men and 2.13; 1.52–2.90 in women) were greater in patients with BD than in the general population. There were significantly increased risks for these solid cancers: colorectal (4.26; 1.38–9.94), liver (4.00; 1.09–10.25), bone/articular cartilage (55.66; 1.41–310.14), prostate (7.05; 1.45–20.60), and brain/central nervous system (28.32; 3.43–102.31) in men; and the lips/oral cavity/pharynx (13.97, 1.69–50.47), liver (12.78; 5.14–26.33), lungs (4.35; 1.18–11.13), other female genital organs (53.57; 1.36–298.49), and eyes (128.26; 3.24–714.59) in women. Patients with BD had a greater risk of myelodysplastic syndrome (MDS) than the general population did (65.72; 7.96–237.41 in men and 53.86; 11.11–157.40 in women), but not of hematological cancer.ConclusionsCompared to the general population, Korean patients with BD had greater risks of overall cancer, some solid cancers, and MDS, but not of hematological cancer.