Abstract 5024: Multiple biomarker combination increased both versatility and recurrence-predictive accuracy of molecular deep surgical margin in head and neck squamous cell carcinoma
Authors: Masamichi Hayashi , Koch Wayne M. , Kodera Yasuhiro 
Published: July 2016

Abstract
Oncologic evaluation of surgical margins has long depended on visible histologic diagnosis. Although intraoperative cytology or frozen section diagnosis directs surgery to be performed in a more adequate way, some histologic negative surgical margins still have genetic or epigenetic alterations associated with disease recurrence in head and neck squamous cell carcinoma (HNSCC). This phenomenon may be partly explained by “field cancerization” or “tumor budding”. In order to further evaluate the locoregional recurrences from histologically negative deep surgical margins, we conducted molecular deep surgical margin analysis using prospectively collected HNSCC surgical samples.
Surgical specimens were collected from consecutive patients with head and neck cancer from whom written informed consent was obtained at Johns Hopkins Hospital (Baltimore, MD) between May 2009 and December 2013. Surgical margins of all cases were histologically negative. Deep surgical margin tissues (n = 70) were collected, and DNA extraction, bisulfite treatment and quantitative MSP (QMSP) assay were performed for three candidate genes (PAX5, VGF and ZNF420).
First, methylation status of all 70 main tumors were examined. PAX5 methylation was detected in 50 cases (71%), VGF methylation in 34 cases (49%) and ZNF420 methylation in 25 cases (36%). Among the cases with PAX5 methylation positive tumors, PAX5 methylation of deep surgical margin tissue was positive in 10 cases and negative in 40 cases. The locoregional recurrence free survival (LRFS) of the cases with methylation-positive margin was worse than those with negative margin (P = 0.059, log-rank test), but not significant. Similarly, LRFS difference between the cases with VGF methylated margin (14 cases) and those with unmethylated margin (20 cases), and the cases with ZNF420 methylated margin (5 cases) and those with unmethylated margin (20 cases) were not significant (P = 0.606, P = 0.059, log-rank test). Then, we combined these three gene markers and defined the case with at least one marker-positive surgical margin as margin positive. As a result, among total 62 cases (89%), margin positive 22 cases showed significantly worse LRFS than margin negative 40 cases (P = 0.021, log-rank test).
Although the case coverage rate of each individual marker was relatively low, marker combination improved it up to 89% of all cases. Optimized gene marker combination would help us not only to detect histologically undetected cancerous cells but also to predict locoregional tumor recurrences.
Citation Format: Hayashi Masamichi, Wayne M. Koch, Yasuhiro Kodera. Multiple biomarker combination increased both versatility and recurrence-predictive accuracy of molecular deep surgical margin in head and neck squamous cell carcinoma. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 5024.