Intraoperative molecular margin analysis in head and neck cancer

Background: Tumor-specific molecular alterations in surgical margins have been shown to predict risk of local recurrence. However, assays used for these analyses are time-consuming and therefore cannot be used in the intraoperative setting. Objective: To detect and quantify tumor-specific methylated promoter sequences in surgical margins in a time frame suitable for intraoperative use. Design: A novel quantitative methylation-specific polymerase chain reaction (QMSP) protocol. Methods: A total of 13 patients with head and neck squamous cell carcinoma (HNSCC) were initially characterized for molecular alterations in their tumor at the time of biopsy. Six primary tumors were found to harbor promoter hypermethylation for p16 and O-6-methylguanine-DNA-methyltransferase (MGMT) genes. Rapid QMSP was then used to identify promoter hypermethylation of these genes in the surgical margins. Results were compared with standard intraorperative histologic frozen section analysis and with conventional QMSP. Results: Using our rapid QMSP assay, we found that 3 patients had methylation-positive margins. Tumor margins from 2 patients were methylated for p16 alone, and margins from I patient were methylated for p16 and MGMT simultaneously. Molecular margin analysis was completed in less than 5 hours, a time frame appropriate for selected major HNSCC resections that require combined primary tumor resection, cervical lymphadenectomy, and complex reconstruction. This technique was comparable in sensitivity to conventional QMSP. Conclusion: Rapid molecular margin analysis using QMSP is feasible and may be performed intraoperatively in selected patients with HNSCC that requires extensive resection.