Criteria for the diagnosis of extra nodal extension detected on radiological imaging in head and neck cancer: HNCIG international consensus recommendations

Extranodal extension of tumour on histopathology (pENE) is known to be a negative prognostic factor in head and neck cancer (HNC). Compelling evidence suggests that extranodal extension detected on radiological imaging (imaging-detected ENE; iENE) is also a negative prognostic factor. Furthermore, if iENE could be identified reliably before start of treatment, it could be used to guide treatment selection, as patients with iENE may be better managed with non-surgical approaches to avoid the toxicity and cost of trimodality therapy. There are many aspects of iENE that remain unresolved or which lack consensus – such as the criteria to best diagnose iENE and the associated terminology. The Head and Neck Cancer International Group conducted a five-round modified Delphi process with a group of 18 international radiology experts, representing 14 national clinical research groups.
We generated consensus recommendations on the terminology and diagnostic criteria for iENE to harmonize clinical practice and research. These recommendations have been endorsed by 19 national organisations, representing 34 countries. We propose a new classification system to aid diagnosis, which was supported by the majority of participating experts over existing systems, and which will require validation in the future. Additionally, we have created an online educational resource for grading iENE.