Podoplanin and ABCG2: malignant transformation risk markers for oral lichen planus.

Oral lichen planus (OLP) is a potentially malignant disorder associated with an increased risk for oral cancer. The purpose of this study was to determine protein expression of podoplanin and ATP-binding cassette, G2 subfamily (ABCG2) in patients with OLP and evaluate their use as biomarkers for OLP malignant transformation risk. Podoplanin and ABCG2 expressions were determined in samples from 110 patients with untransformed OLP and 9 patients with malignant transformed OLP (mean follow-up of 5.1 years). We compared podoplanin expression, ABCG2 expression, and clinicopathologic parameters between the two groups. Podoplanin expression was observed in 48 of 110 (43.6%) cases of untransformed OLP and in 8 of 9 (88.9%) cases of transformed OLP. ABCG2 expression was found in 23 of 110 (20.9%) cases of untransformed OLP and in 6 of 9 (66.7%) cases of transformed OLP. Multivariate regression analysis revealed that podoplanin or ABCG2 expression was associated with 17.13-fold [95% confidence interval (95% CI), 1.71-171.22; P = 0.016] or 6.04-fold (95% CI, 1.20-30.36; P = 0.029) increased risk of malignant transformation, respectively. The risk of OLP malignant transformation was considerably higher with coexpression of podoplanin and ABCG2 than without coexpression of podoplanin and ABCG2 (odds ratio, 25.24; 95% CI, 4.48-142.27; P < 0.001). The expressions of podoplanin and ABCG2 in OLP were significantly associated with malignant transformation risk. Our data suggested that podoplanin and ABCG2 may be used as biomarkers for risk assessment of oral malignant transformation in patients with OLP.