Retrospective cohort study of cancer risk in patients with overall and site-specific lichen planus

The association between lichen planus (LP) and subsequent cancer risk, particularly by anatomical site, is not well established. A retrospective cohort study using nationwide Danish register-based data of individuals with an incident LP diagnosis (1978-2020) with no prior cancer assessed the association between any LP, and site-specific LP, and the subsequent risk of cancer compared to the general population. A total of 35 845 patients with LP (21 650 females and 14 195 males) with follow-up through 2023 were included in the analysis. Both females and males had increased risks of oral, cutaneous, and genital cancers, compared to the general population. Oral LP showed a 9- to 14-fold increased risk of oral cancers, while genital LP showed a 17- to 24 fold increased risk of genital cancers, with associations persisting over time. The authors conclude that these findings may guide long-term follow-up regarding cancer risk in LP patients, particularly in patients with oral or genital disease.