Purpose: To study the role of computed tomography in the pre-therapy evaluation of nasopharyngeal carcinoma.
Methods and materials: The computed tomography of 119 new patients of nasopharyngeal carcinoma were evaluated independent of clinical findings for neck node metastases, and then compared with clinical findings. Contrast enhanced axial scans were obtained at 5 mm intervals with the infraorbitomeatal line parallel to the gantry. Scans were obtained from the supra-sellar cistern to the C5 or C6 vertebra for the evaluation of the base of skull, nasopharynx, paranasopharyngeal space and the upper and mid neck.
Result: The present study confirmed the disparity of nodal extent documented by clinical palpation and computed tomography. Of the 37 patients who have no clinically palpable node (N0), computed tomography showed nodal involvement in 11 (29.7%) of them, and they were up-staged from N0 to N1. Computed tomography showed multiple or bilateral nodes in seven (58.3%) of the 12 patients with AJC N1 disease and they were hence up-staged to N2. All together, there were 28 (23.5%) patients who have no computed tomography evidence of nodal involvement by tumor. In agreement with clinical experience, the most commonly involved nodal groups were the upper internal jugular and upper spinoaccessary, followed by the lateral retropharyngeal. The percentage of nodes which were not clinically palpable was roughly the same for different regions (15-30%), except, as expected, that all the retropharyngeal nodes were not palpable. The risk of harboring retropharyngeal node was proportional to the size of the largest node in the ipsilateral neck.
Conclusion: A significant proportion of patients with clinically negative neck (N0) or AJC N1 disease will be upstaged by computed tomography, thus supporting its routine use in pre-therapy evaluation of nasopharyngeal carcinoma.