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Open Access Research article

A new T classification based on masticator space involvement in nasopharyngeal carcinoma: a study of 742 cases with magnetic resonance imaging

Dong-Hua Luo12, Jing Yang12, Hui-Zhi Qiu13, Ting Shen12, Qiu-Yan Chen12, Pei-Yu Huang12, Rui Sun12, Chao-Nan Qian12, Hai-Qiang Mai12, Xiang Guo12 and Hao-Yuan Mo12*

Author Affiliations

1 State Key Laboratory of Oncology in South China; Collaborative Innovation Center for Cancer Medicine, Sun Yat-sen University Cancer Center, Guangzhou, PR China

2 Department of Nasopharyngeal Carcinoma, Sun Yat-sen University Cancer Center, 651 Dongfeng Road East, Guangzhou, Guangdong 510060, PR China

3 Department of Radiotherapy, Affiliated Cancer Center, Guangzhou Medical College, Guangzhou, Guangdong 510095, PR China

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BMC Cancer 2014, 14:653  doi:10.1186/1471-2407-14-653

Published: 4 September 2014

Abstract

Background

The aim of this study was to investigate the prognostic significance and various classifications for anatomic masticator space involvement (MSI) in patients with nasopharyngeal carcinoma (NPC).

Methods

This study retrospectively analyzed 742 patients with untreated nondisseminated NPC who underwent magnetic resonance imaging (MRI) scan of the nasopharynx and neck. The MSI was graded according to different anatomic features. The overall survival (OS), local relapse-free survival (LRFS), distant metastasis-free survival (DMFS), and disease-free survival (DFS) of the patients with different MSI grades were analyzed using the Kaplan-Meier method and log-rank tests.

Results

The frequency of MSI was 24.1% (179/742). The 5-year OS, LRFS, DMFS, DFS for NPC patients with versus without MSI were 70.9% versus 82.5% (P = 0.001), 94.1% versus 91.4% (P = 0.511), 81.4% versus 88.7% (P = 0.021), and 78.0% versus 83.5% (P = 0.215), respectively. Significant differences in OS were also found among different MSI groups. In the patients with MSI, the OS of the group with medial and/or lateral pterygoid involvement (MLPI) NPC was 73.9% compared to 51.3% (P < 0.0001) in the patients with infratemporal fossa involvement (IFI).

Conclusions

MSI was an independent prognostic factor for OS and DMFS. NPCs invading the masticator space should be separately categorized into MLPI and IFI prognostic groups. We suggest that MLPI should be staged as T3 while IFI is staged as T4 disease in future TNM staging revision.

Keywords:
Nasopharyngeal carcinoma; Masticator space involvement; Magnetic resonance imaging; Prognosis