A histopathological appraisal of surgical margins in oral and oropharyngeal cancer resection specimens

Summary

Standardised reporting of head and neck cancer resections according to guidelines issued by the UK Royal College of Pathologists was introduced as a routine procedure in 1998. The guidelines include definitions of “mucosal”, “deep”, “clear”, “close” and “involved” surgical margins. This study of routine diagnostic material describes the frequency, type and morphological features of involved margins, and assesses the influence of tumour site and pathological T and N stage. 301 consecutive radical resection specimens for oral/oropharyngeal squamous cell carcinoma assessed according to the guidelines were appraised. 70 resections (23%) had involved margins. The frequency was related to primary tumour site, and pathological T and N stage. Mucosal involvement was evident in 11 resections, bone in 10, and deep soft tissue in 61–12 resections had multiple category involvement. Both anatomical factors and histological “markers” of tumour characteristics influence the status of surgical resection margins.

Introduction

Assessment of the resection margins forms an important part of the pathological examination of surgical specimens in patients undergoing surgery with curative intent for most forms of malignant disease, including squamous cell carcinoma of the mouth and oropharynx (OSCC). Although the histopathologic status of the resection margins has long been used as a potential indicator of local recurrence and survival, there is still considerable uncertainty concerning many aspects of resection margins including their nomenclature and definition, and the influence of anatomical and histological factors.¹ The UK Royal College of Pathologists issued guidelines and a minimum dataset for head and neck carcinomas in 1998² in an attempt to improve and standardise cancer services in line with the Calman–Hine Report.2, 3 The Guidelines divided the surgical margins into “mucosal” and “deep” and in each category, defined a histological distance from invasive carcinoma to surgical margins of more than 5 mm as clear, 1–5 as close and less than 1 mm as involved. Involved cases may, or may not, show histological cut-through.² However, to date, there have been no studies of resection specimens reported according to those criteria. In particular, there is no information on the morphological features of “involved” margins. A retrospective review of the Oral Pathology Diagnostic Service at the Liverpool University Dental Hospital showed that 301 surgical resection specimens for OSCC have been reported since the introduction of the Guidelines. This material provided us with the opportunity to remedy the aforementioned deficiencies and the present investigation was undertaken. Our aims were (1) to determine the relative frequency of involved versus close and clear margins; (2) to assess the influence of tumour site and pathological T and N status, and pathological stage⁴ on the relative frequency of the three categories; (3) in the cases of involved margins, to determine the relative frequency of involved mucosal and deep margins; and (4) to seek possible histological explanations for the involved status.