Conversion of T-stages of nasopharyngeal carcinoma by computed tomography

Thirty-six patients with nasopharyngeal carcinoma (NPC) were examined with computed tomography (CT) before definitive radiation therapy. CT clearly delineated the extent of the primary tumors. CT frequently showed subtle destruction of the paranasal sinuses and pterygoid plate, which was not usually detected by conventional X ray examinations. T-staging was made according to the UICC TNM classification system (1978) or another system, depending on clinical findings and the conventional X ray examinations (non-CT T-stage). Then, the non-CT T-stage of each patient was compared with T-stage diagnosed with CT findings alone (CT T-stage). CT upstaged non-CT T-stage in 14 of the 36 patients according to either system. Only one patient was downstaged by CT; this patient had cranial nerve palsy but not detectable bone destruction as shown by CT. We conclude that CT is the single, most reliable imaging method for primary tumors of NPC patients. Since CT detects subtle bone destruction, however, a large number of patients will be classified as having advanced tumors. Further modification of the TNM system may be needed for NPC patients in this era of CT.