Lichen sclerosus and risk of cancer.

Malignant potential of lichen sclerosus (LS) has been suspected, but evidence is sparse. We used the population-based Finnish Cancer Registry data to further study this connection. We identified all women with the diagnosis of LS (n = 7,616) listed in the Finnish Hospital Discharge Registry from 1970 to 2012. The cohort was followed through the Finnish Cancer Registry for subsequent cancer diagnoses until 2014. Standardized incidence ratios (SIRs) were calculated for different cancers by dividing the observed numbers of cancers by expected ones. The expected numbers were based on national cancer incidence rates. During the follow-up period, we found 812 cancers among patients with LS (SIR: 1.13, 95% CI 1.05-1.21). LS was associated with an increased risk of vulvar (182 cases, SIR: 33.6, 95% CI 28.9-38.6) and vaginal cancer (4 cases, SIR: 3.69, 95% CI 1.01-9.44). The risk of cancers of the uterine cervix and lung was significantly decreased. LS is associated with an increased risk for vulvar and vaginal cancer. These data are important when designing the care of women diagnosed with LS.