Risk of solid malignancies in bullous pemphigoid: A large‐scale population‐based cohort study

The association of bullous pemphigoid (BP) with solid malignancies (SM) is a matter of controversy, as previous studies produced inconclusive findings. The aim of this study was to assess the risk of SM among patients with BP and to evaluate whether a history of SM predisposes individuals to develop subsequent BP. A population-based cohort study was performed comparing BP patients (n = 3924) with age-, sex- and race-matched control subjects (n = 19 280) with regard to incident cases of SM. Adjusted hazard ratios (HR) and adjusted odds ratios (OR) were estimated by Cox regression and logistic regression, respectively. The incidence of SM was 13.4 (95% confidence interval [CI], 11.6-15.3) and 14.3 (95% CI, 13.5-15.1) per 1000 person-years among patients with BP and controls, respectively. BP was not associated with an increased risk of SM (adjusted HR, 0.90; 95% CI, 0.77-1.05). Additionally, a history of SM was not related to the risk of subsequent BP (adjusted OR, 1.00; 95% CI, 0.90-1.10). In a stratified analysis, patients with BP had an increased risk of uterine cancer (adjusted HR, 2.56; 95% CI, 1.39-4.72) unlike the 18 remaining analyzed types of SM. Relative to BP patients without SM, those with BP and SM were older, had a male predominance, a higher prevalence of smoking, a higher burden of comorbidities and comparable survival rates. Although patients with BP do not experience an overall increased risk of developing SM, they are more likely to have uterine cancer. Our findings argue against routine extended cancer screening for patients with incident BP, but raise the awareness of uterine cancer among females with BP.