High-grade radiologic extra-nodal extension predicts distant metastasis in stage II nasopharyngeal carcinoma.

Background To investigate the prognostic value of radiologic extra-nodal extension (rENE) in stage II nasopharyngeal carcinoma (NPC). Methods Stage II NPC patients with N1 category (n = 365) were enrolled and divided into three groups according to the situation of rENE: without rENE, suspected rENE, and confirmed rENE (grades: A, infiltration into surrounding fat; B, matted nodes; C, infiltration into adjacent structures). Results Only high-grade rENE (including matted nodes and infiltration into adjacent structures) could significantly influence the survival outcomes, patients with high-grade rENE had significantly poorer survival than those without, with the 7-year distant metastasis-free survival and overall survival demonstrated to be 78.5% vs 93.0% (P < .001) and 81.9% vs 89.9% (P = .05), respectively. High-grade rENE, as defined in our study, is a stable criterion, with high intra-rater and inter-rater consistency. Conclusion High-grade rENE was an evaluable predictor that could help with the selection of stage II patients with high risk of distant metastasis.