Imaging characteristics of nasopharyngeal carcinoma for predicting distant metastasis

Abstract

Aim: To determine the imaging characteristics of nasopharyngeal carcinoma (NPC) that may be associated with increased risk of distant metastasis.

Materials and methods: A total 164 patients with NPC were reviewed retrospectively. Patients were divided into the metastatic group (n=110) or the non-metastatic group (n=54). Non-metastatic was defined as no evidence of distant metastasis during at least 5 years of follow-up. Pretreatment images of the primary tumour and nodal involvement were analysed. Statistical analyses were performed to identify the factors that may predict distant metastasis.

Results: The statistically significant sites of tumour extension in the metastatic group included: skull base bone (p<0.001), cervical spine (C-spine; p=0.012), parapharyngeal space (p=0.003), pterygopalatine fossae (PPF; p=0.004), prevertebral space (p<0.001), masticator space (p=0.006), carotid space (p=0.001), and intracranial extension (p=0.004). Statistically significant nodal involvement included bilateral involvement (p=0.04), size 3-6 cm (p=0.011), >10 pathological nodes (p<0.001), level IB (p=0.013), IIB (p=0.011), III (p=0.001), IV (p<0.001), VB (p=0.001), and supraclavicular (p=0.003) and intraparotid nodes (p=0.004). The mean number of significant involvement factors was significantly higher in the metastatic group (3.46±2.24 tumour extension sites and 5.04±2.51 nodal involvement factors) than in the non-metastatic group (p<0.001).

Conclusion: NPC patients with local extension at more than three sites and with more than five nodal involvement factors should be screened for distant metastasis.