N-staging of nasopharyngeal carcinoma: Discrepancy between UICC/AJCC and Ho systems

Abstract

To enable clinicians to have a better understanding of the limitations of the UICC/AJCC and Ho N-staging systems for nasopharyngeal carcinoma, 4730 patients without distant metastases at diagnosis were retrospectively analysed. The two systems agreed in 54% (1867/3451) of node-positive patients, and their treatment results were taken as the reference for comparison. To identify the most appropriate N-stage for the discrepant groups, their outcomes were measured against the respective reference. All patients with single, ipsilateral and small nodes, irrespective of their relative position in the upper-mid neck should be classified as N1, while those with multiple, bilateral/contralateral or medium-sized node(s) are effectively N2, even if nodal involvement is confined to the upper neck. All patients with extension to the supraclavicular fossa (irrespective of size) and those with nodes larger than 6 cm at the greatest diameter (irrespective of level) should be classified and treated as N3, especially as, in this group, half of the patients died of distant metastases and trials of adjuvant systemic therapy have to be considered. Areas of inaccurate prognostication by the respective system should be noted to avoid misguiding treatment strategy. The present analyses support our previous suggestions that both the level of extent and the bulk of nodal deposits are important prognostic factors. While supraclavicular involvement is a significant demarcation, there is little justification for further division into upper and mid-levels. The merits of both systems should be duly recognized and combined for the further improvement of prognostic accuracy.