Imaging-derived Extranodal Extension (iENE) in Head and Neck Cancer
This guide from the AOSNHNR-ASHNR-ESHNR Joint Task Force offers radiologists a clear framework for identifying and reporting imaging-derived extranodal extension (iENE) in head and neck cancer, supporting consistent interpretation and better patient care.
Introdcution
Pathologic extranodal extension of metastatic tumor has been shown to be a risk factor for multiple types of cancers in the head and neck. For several years, the radiology community has attempted to determine whether imaging modalities could detect pENE without the need for surgical excision of the affected lymph nodes. More recent studies have shown, however, that iENE represents an independent risk factor for disease-free and overall survival of patients with HNSCC from various primary sites, including NPC and OPSCC. Thus, in the 9th version of the AJCC Staging Manuals, iENE appears as an independent risk factor for clinically upclassifying the lymph nodes in some types of HNSCC, without regard to the pENE status of those nodes.
The goal of this Guide is to provide educational materials for radiologists regarding the diagnosis of iENE, to ensure consistent application of standards and thresholds for positivity. Previous literature has demonstrated weak inter-rater consistency when diagnosing iENE, but these measures are improved with educational and self-assessment tools. This Guide was created by a collaborative task force comprising members of the ASHNR, ESHNR, and AOSNHNR with research and clinical experience regarding iENE. The six members of the committee are radiologists practicing in six different countries, with two members representing each of the sponsoring organizations. This Guide is based on, and aligns with, the classification scheme advocated by the HNCIG.
Perhaps the most important overarching philosophy, as emphasized by the AJCC and UICC, is that indeterminate or equivocal findings should be regarded as “negative” for iENE. Although radiologists may choose to report equivocal findings for radiotherapy planning, only definitive, unequivocal radiologic findings should be used during staging to assign the N category. The reasoning behind this decision is that patients who are improperly upstaged may be denied potentially curative surgery or unnecessarily subjected to the morbidity of chemoradiation.