Extent of paranasal sinus involvement and its prognostic value in nasopharyngeal carcinoma: Proposed modification in the current UICC/AJCC staging system

Abstract

PurposeThis study aimed to evaluate the prognostic value of paranasal sinus involvement (PSI) in NPC and to explore its appropriate position in the current AJCC staging system. Materials and methodsPretreatment MRI of 1317 patients with NPC treated with intensity-modulated radiotherapy (IMRT) between January 2010, and January 2013, were reviewed retrospectively. Survival was compared between patients with PSI-slight (sinus bone wall erosion only) and PSI-severe (tumor penetrated into sinus cavity). Multivariable analysis was performed to identify the independent predictors of survival. ResultsThe study included 1317 patients (median age 46 years; range, 11–78 years). PSI-slight was present in 15.2% (200/1317) patients and PSI-severe in 20.0% (263/1317) patients. Overall survival (OS), distant metastasis–free survival (DMFS), loco-regional recurrence–free survival (LRFS), and progression-free survival (PFS) were significantly lower in patients with PSI-severe (all P < .05). In multivariable analysis, PSI-severe was an independent prognostic factor for OS, DMFS, LRFS, and PFS (all P < .05). 96 AJCC T3 category patients with PSI-severe were reclassified as T4 category. The revised T category had significantly better predictive value (higher C-index) than that the AJCC system for survival (OS, .661 vs. .652; DMFS, .655 vs. .650; P < .05 for all). ConclusionPSI-severe is an independent negative prognostic factor in nasopharyngeal carcinoma, which is recommended to be classified as T4 category in the 8th AJCC staging system for NPC.