Familial Nasopharyngeal Carcinoma 6

Staging of Nasopharyngeal carcinoma 315Table 24.2. Significance of original and modified T-categories by multivariate analysisT-categoryHazard ratio (95% confidence interval)Original 5th and 6th edition TNMLocal recurrence Distant failure Cancer-specific deathT1T2aT2bT3T411.24 (0.75–2.06)1.80 (1.20–2.69)2.51 (1.62–3.87)3.17 (2.08–4.83)10.70 (0.44–1.12)0.33 (0.97–1.84)1.42 (0.99–2.05)2.17 (1.55–3.05)Modified TNM with T2a considered to be T1, and T2b considered to be T2T1T2T3T411.62 (1.18–2.22)2.26 (1.59–3.22)2.86 (2.04–4.01)11.54 (1.17–2.03)1.63 (1.18–2.25)2.50 (1.86–3.36)10.96 (0.59–1.55)1.42 (0.996–2.03)1.83 (1.24–2.71)3.01 (2.09–4.32)11.45 (1.08–1.94)1.86 (1.33–2.60)3.05 (2.26–4.13)Adapted from Lee et al. (2004)Fig. 24.2. Axial T1 magnetic resonance weighted image showstumor extending to involve the right poststyloid parapharyngealspace (PPS) (dashed arrow). The two dark roundedstructures are the carotid and jugular vessels which are encasedby tumor. The normal PPS fat is seen on the left side asa wedge-shaped area of bright T1 signal (solid arrow)compartments of the PPS are radiographically visibleon MRI. For example, infiltration of the fatty componentof the PPS is often visible on T1-weighted imaging(Fig. 24.2). This appears as intermediate signaltumor and invades into the bright fat of the PPS. Also,it is often possible to delineate the pharyngobasilarfascia (PBF), the tensor veli palatini and levator palatinimuscles which are key components in the delineationof the PPS. Violation of the PBF (Fig. 24.3),infiltration of the tensor veli palatini, and breach ofthe pharyngeal portion of the levator veli palatinimuscle are radiographically consistent with PPSinvolvement.The traditional AJCC TNM classification criterionfor defining infratemporal fossa extension is thepresence of disease beyond the anterior surface ofthe lateral pterygoid muscle, or lateral extensionbeyond the postero-lateral wall of maxillary antrumor pterygomaxillary fissure (Fleming et al. 1997).The UICC on the other hand did not specify a definitionand some centers may use an alternative definition,for example employing a line drawn from thefree edge of the medial pterygoid plate to the lateralsurface of the carotid artery for demarcation (Lee etal. 2004). The term masticator space was added as oneof the criteria for T4 in the UICC/AJCC 6th edition,and considered as synonymous with infratemporalfossa and has used the same definition (Greene et al.2002). Both terms are currently used to both acknowledgethe traditional method described by Ho (Ho1978b) and to allow the more favored contemporaryapproach used by radiologists. In reality, most headand neck radiologists would prefer to exclusively usethe term masticator space. As discussed below, it isclear is that they are not synonymous, and resolutionof this controversy is probably needed to avoid