The role of Epstein-Barr virus-encoded microRNA BART7 status of resection margins in the prediction of local recurrence after salvage nasopharyngectomy for recurrent nasopharyngeal carcinoma

Abstract

BACKGROUND Local recurrence is the major cause of treatment failure in patients who undergo surgical salvage of recurrent nasopharyngeal carcinoma (NPC) after radiotherapy. The authors investigated the role of Epstein-Barr virus (EBV)-encoded Bam HI-A rightward transcript 7 microRNA (BART7) status in resection margins in the identification of a subgroup of patients who may benefit from adjuvant reradiation after surgery. METHODS One hundred two consecutive patients who had histologically clear resection margins after undergoing nasopharyngectomy for recurrent NPC were studied. The status of EBV microRNA BART7 in resection margins was investigated and correlated with the pattern of subsequent disease recurrence. RESULTS After a median follow-up of 64 months, 20 patients (19.6%) developed local recurrence after surgery despite histologically uninvolved margins. The risk of local recurrence in patients with histologically close (<5 mm) and clear (≥5 mm) margins was 31.6% and 12.5%, respectively. In patients with clear histologic margins, those with margins that were positive for EBV microRNA BART7 has a significantly higher chance of developing local tumor recurrence (P=.016) than those with negative molecular margins. The difference was not significant when the histologic clearance at the resection margins was <5 mm. CONCLUSIONS Tissue EBV microRNA BART7 is useful for identifying a subgroup of patients with histologically clear margins who are at increased risk of subsequent local tumor recurrence. Postoperative adjuvant treatment is warranted for these patients. Cancer 2015;121:2358-2366.