Susceptibility and Prevention Δ Np 63 Overexpression , Alone and in Combination with Other Biomarkers , Predicts the Development of Oral Cancer in Patients with Leukoplakia

Purpose: The risk of malignant transformation of oral preneoplastic lesion (OPL) is difficult to assess. ΔNp63 is an early oncoprotein associated with mucosal tumorigenesis. The purpose of this study was to assess ΔNp63 expression in OPL and its role as a marker of oral cancer risk. Experimental Design: ΔNp63 expression was determined using immunohistochemistry in 152 OPL patients included in a clinical trial comparing retinyl palmitate alone or plus β-carotene with low-dose 13-cis-retinoic acid. The associations between ΔNp63 expression as well as ΔNp63 expression with other potential risk factors for oral cancer development were analyzed. Results: ΔNp63 expression was positive in 41 (27%) patients, clusters of intraepithelial inflammatory cells (EIC) were noted in 37 (26%) patients, and podoplanin (previously reported) was positive in 56 (37%) patients. Significantly more patients whose lesions were ΔNp63 positive or exhibited EIC developed oral cancers. In the multicovariate analysis including age, treatment, and histologic status as cofactors, positive ΔNp63 expression was associated with an increased hazard ratio of 3.308 (95% confidence interval, 1.663-6.580; P = 0.0007). Patients whose lesions showed positive ΔNp63, podoplanin, and EIC had the highest oral cancer risk with a hazard ratio of 4.372 (95% confidence interval, 1.912-9.992; P = 0.0005) and 61% oral cancer development rate at 5 years compared with 15% of other OPL patients (P < 0.0001). Conclusion: ΔNp63 overepression in OPL is associated with increased oral cancer risk. Together, ΔNp63, podoplanin, and EIC may be used as biomarkers to identify OPL patients with substantially high oral cancer risk. (Clin Cancer Res 2009;15(19):6284–91) Oral cancer is common worldwide. Leukoplakia is the most commonly diagnosed oral preneoplastic lesion (OPL) in the oral cavity (1), with a rate of malignant transformation between 17% and 24% during periods of up to 30 years (2–4). Prevention of malignant transformation is particularly important in view of the poor prognosis associated with oral squamous cell carcinoma (5). Clinical predictors of malignant transformation in oral leukoplakia have been recently reviewed (6). Although they are important, they are nonspecific and interdependent to some degree. Lesions with dysplastic features remain the most important indicator for risk of oral cancer in the population. However, the predictive value of dysplasia is insufficient, and more important, the majority of oral cancers develop from lesions that lack dysplastic changes (2, 3, 7). Few prevention studies have shown efficacy in preventing malignant transformation of leukoplakias (8). One of the major difficulties in OPL prevention trials is identification of patients with higher cancer risk (9). Toward this need, we recently showed that podoplanin, together with histologic status, was a promising biomarker for predicting the risk of oral cancer development (10). To further improve our risk assessment model, we are exploring additional molecular markers using the same patient population. We selected ΔNp63 in this study because it is a homologue of the p53 tumor suppressor (11) and frequently amplified and overexpressed in squamous cell carcinomas, including head and neck squamous cell carcinoma (HNSCC; refs. 12–15). In normal oral mucosa and reactive epithelial hyperplasia, ΔNp63 expression is only observed in the basal layer, with Authors' Affiliations: Departments of Thoracic/Head and Neck Medical Oncology, Biostatistics and Applied Mathematics, and Pathology, The University of Texas M. D. Anderson Cancer Center, Houston, Texas; and Department of Oncology and Diagnostic Sciences, University of Maryland Dental School, Baltimore, Maryland Received 2/26/09; revised 5/14/09; accepted 5/15/09; published OnlineFirst 9/22/09. Grant support: National Cancer Institute grants PO1 CA106451, P50 CA97007, and P30 CA16672. The costs of publication of this articleweredefrayed in part by the payment of page charges. This article must therefore be hereby marked advertisement in accordancewith 18 U.S.C. Section 1734 solely to indicate this fact. Requests for reprints: Li Mao, Department of Oncology and Diagnostic Sciences, University of Maryland Dental School, 650 West Baltimore Street, Baltimore, MD 21201. Phone: 410-706-4339; Fax: 410-706-6115; E-mail: lmao@umaryland.edu. F 2009 American Association for Cancer Research. doi:10.1158/1078-0432.CCR-09-0498 6284 Clin Cancer Res 2009;15(19) October 1, 2009 www.aacrjournals.org Research. on April 14, 2017. © 2009 American Association for Cancer clincancerres.aacrjournals.org Downloaded from Published OnlineFirst September 22, 2009; DOI: 10.1158/1078-0432.CCR-09-0498