Prognostic Value of Classifying Parapharyngeal Extension in Nasopharyngeal Carcinoma Based on Magnetic Resonance Imaging

Table 2

Incidence of tumor parapharyngeal extension by anatomic site.

Anatomic site	Death		Local failure		Distant metastasis
	HR^* (95% CI)		HR^* (95% CI)		HR^* (95% CI)
Masticator space
None	0.551 (0.400–0.760)	<0.001	0.457 (0.267–0.782)	0.004	0.394 (0.256–0.606)	<0.001
Medial pterygoid muscle	0.623 (0.445–0.873)	0.006	0.940 (0.566–1.561)	0.812	0.584 (0.386–0.884)	0.011
Lateral pterygoid muscle	1		1		1
Staging masticator space	0.906 (0.522–1.573)	0.727	1.147 (0.467–2.819)	0.765	1.067 (0.563–2.023)	0.842
Masticator space
None	0.885 (0.651–1.202)	0.433	0.486 (0.302–0.780)	0.003	0.675 (0.439–1.037)	0.073
Medial pterygoid muscle	1		1		1
Lateral pterygoid muscle and beyond	1.572 (1.143–2.163)	0.005	1.091 (0.678–1.754)	0.720	1.734 (1.172–2.567)	0.006
Carotid space
None	0.735 (0.586–0.921)	0.008	0.693 (0.482–0.996)	0.048	0.689 (0.502–0.947)	0.022
Anterior carotid space	1		1		1
Posterior carotid space	1.085 (0.787–1.497)	0.618	1.035 (0.802–1.507)	0.621	1.425 (0.952–2.132)	0.085
Parapharyngeal extension
None	0.678 (0.494–0.931)	0.016	0.659 (0.395–1.099)	0.110	0.832 (0.523–1.325)	0.439
Paranasopharyngeal	1		1		1
Paraoropharyngeal	1.169 (0.756–1.809)	0.482	1.734 (0.952–3.158)	0.072	1.257 (0.857–2.213)	0.312

^*HR adjusted for age, gender, chemotherapy, T category, and N category according to the seventh edition AJCC system.