DNA Methylation and P53 Immunohistochemistry as Prognostic Biomarkers for Vulvar Lichen Sclerosus.

ABSTRACT

Vulvar lichen sclerosus (LS) is an inflammatory dermatosis which can progress to human papillomavirus (HPV-)independent vulvar intraepithelial neoplasia (HPVi VIN) and vulvar squamous cell carcinoma (VSCC). Although LS has a much lower cancer risk compared to HPVi VIN (5% versus 50%, respectively), its incidence is significantly higher. Therefore, there is a clinical need to identify LS patients with an increased cancer risk. Our objective was to study the value of DNA methylation and p53 immunohistochemistry (IHC) as prognostic biomarkers for progression to cancer in patients with LS. Vulvar tissues from 236 patients were selected, including 75 LS and 68 HPVi VIN, both with and without cancer development, 32 VSCC and 61 healthy vulvar controls. Samples were subjected to p53 IHC and DNA methylation analysis of a three-gene marker panel containing ZNF582, SST and miR124-2. Methylation levels and p53 IHC status (mutant or wild-type) were assessed and compared among all disease categories. Odds ratios (ORs) were determined to identify whether the biomarkers were associated with progression to cancer in patients with LS. Highest methylation levels were found in HPVi VIN and VSCC, followed by LS and healthy vulvar controls. The largest heterogeneity in methylation levels was observed in LS cases. In fact, the three-marker panel tested positive in 70% of LS which progressed to VSCC versus only 17% of LS in patients without cancer development (p=0.002). Also, mutant p53 IHC was observed more frequently in LS with progression to VSCC as compared to non-progressive LS cases (42% versus 3%, respectively, p=0.001). Multivariable analysis identified a mutant p53 status as the only independent risk factor for cancer development in LS (OR 34.0, 95% CI 1.4 - 807.4). In conclusion, DNA methylation testing and p53 IHC show strong potential as prognostic biomarkers for the identification of LS patients at high risk of progression to cancer.