BACKGROUND: Rosacea is a common facial skin disorder with an estimated prevalence of 5-10% among Caucasians.

OBJECTIVE: We compared cancer incidence in patients previously diagnosed with rosacea with that in the general population.

METHODS: Nationwide cohort study of the Danish population using individual-level linkage of administrative registers. All Danish citizens aged ≥18years were followed from January 1st 2008 to December 31st 2012. Patients with rosacea (the exposure) were compared with the general population, serving as control subjects. The outcome was a diagnosis of one of the following cancers: breast, ovarian, endometrial, cervical, kidney, malignant melanoma, non-melanoma skin cancer (NMSC), pancreatic, hepatic, thyroid, esophageal, and lung cancer. Baseline prevalence of cancers were assessed, incidence rates per 1000 person-years were calculated, and hazard ratios (HRs) adjusted for age, sex, socio-economic status, and healthcare consumption were estimated by Cox regression models.

RESULTS: The study comprised a total of 49,475 patients with rosacea and 4,312,213 subjects from the general population. There was no increased risk of malignant melanoma, ovarian, endometrial, cervical, esophageal, kidney, pancreatic, or thyroid cancer. However the risk of hepatic cancer (HR 1.42; 95% confidence interval [CI] 1.06-1.90), NMSC (HR 95% CI 1.36; 1.26-1.47), and breast cancer (HR 1.25; 95% CI 1.15-1.36) was significantly increased, and the risk of incident lung cancer was significantly decreased (HR 0.78; 95% CI 0.69-0.89).

CONCLUSION: We found an increased risk of NMSC, breast cancer, and hepatic cancer, and a reduced risk of lung cancer, among patients with rosacea. These results are in contrast to the limited published data on cancers in rosacea, and further studies are warranted to elucidate the potential relationship between rosacea and various cancers. The findings add to the overall clinical description of patients with rosacea.