BACKGROUND An accurate staging system is crucial for cancer management. Evaluations for continual suitability and improvement are needed as staging and treatment methods evolve. METHODS This was a retrospective study of 1609 patients with nasopharyngeal carcinoma investigated by magnetic resonance imaging, staged with the 7th edition of the American Joint Committee on Cancer (AJCC)/International Union Against Cancer (UICC) staging system, and irradiated by intensity-modulated radiotherapy at 2 centers in Hong Kong and mainland China. RESULTS Among the patients without other T3/T4 involvement, there were no significant differences in overall survival (OS) between medial pterygoid muscle (MP)±lateral pterygoid muscle (LP), prevertebral muscle, and parapharyngeal space involvement. Patients with extensive soft tissue involvement beyond the aforementioned structures had poor OS similar to that of patients with intracranial extension and/or cranial nerve palsy. Only 2% of the patients had lymph nodes>6cm above the supraclavicular fossa (SCF), and their outcomes resembled the outcomes of those with low extension. Replacing SCF with the lower neck (extension below the caudal border of the cricoid cartilage) did not affect the hazard distinction between different N categories. With the proposed T and N categories, there were no significant differences in outcome between T4N0-2 and T1-4N3 disease. CONCLUSIONS After a review by AJCC/UICC preparatory committees, the changes recommended for the 8th edition include changing MP/LP involvement from T4 to T2, adding prevertebral muscle involvement as T2, replacing SCF with the lower neck and merging this with a maximum nodal diameter>6 cm as N3, and merging T4 and N3 as stage IVA criteria. These changes will lead not only to a better distinction of hazards between adjacent stages/categories but also to optimal balance in clinical practicability and global applicability.

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Objective To develop a nomogram for refining prognostication for patients with non-disseminated nasopharyngeal cancer (NPC) staged with the proposed AJCC/UICC 8th edition. Material and methods Consecutive patients investigated by magnetic resonance imaging, staged by the proposed AJCC/UICC 8th edition, and irradiated by intensity- modulated radiotherapy (IMRT) from June 2005 to December 2010 were analyzed. The cohort of 1197 patients treated at Fujian Provincial Cancer Hospital was used as the training set and the results were validated by 412 patients from Pamela Youde Nethersole Eastern Hospital. Cox regression analyses were performed to identify significant prognostic factors for developing a nomogram to predict overall survival (OS). The discriminative ability was assessed with concordance index (C-index). Patients were categorized into three risk groups by performing recursive partitioning algorithm (RPA) on the survival scores of the combined set. Results Multivariable analysis showed that age, gross primary tumor volume (GTV-P) and lactate dehydrogenase (LDH) were independent prognostic factors for OS in addition to stage-group. The OS nomogram based on all these factors had a statistically higher bias-corrected C-index than prognostication based on stage-group alone (0.712 vs 0.622, p<0.01). These results were consistent for both the training and the validation cohorts. Patients with <135 points were categorized as low-risk, ≥135–<160 points as intermediate-risk and ≥160 points as high-risk, respectively. Their 5-year OS rates were 92%, 84% and 58%, respectively. Conclusions The proposed nomogram could improve prognostication when compared with TNM stage-group. This could aid in risk stratification for individual NPC patients.