Using CT or MRI to assess locoregional spread to determine the radiotherapy target of hypopharyngeal carcinoma

Aim: To identify the locoregional extension of hypopharyngeal carcinoma (HPC), particularly the invasion of the nasopharynx and skull base, and metastasis of level VI and retropharyngeal lymph node (RPLN) by investigating computed tomography (CT) and magnetic resonance (MR) images; together with the radiotherapy target of HPC. Methods: CT and MR images of 186 patients with pathologically confirmed HPC between Aug 2000 and Dec 2010 were analyzed retrospectively. We used the χ² test and logistic regression to analyze local invasion and regional spread and to determine their relationships. Results: Of the 186 patients, there was only one case of invasion of the nasopharynx without skull base involvement. The rate of regional node metastasis was 79%. There was no significant relationship between T stage and lymph node metastasis (P = 0.1). Level IV metastasis (P = 0.001), RPLN metastasis (P = 0.041) and esophageal invasion (P = 0.003) were significantly correlated with level VI metastasis. Primary tumor subsite (P = 0.024), bilateral cervical node metastasis (P < 0.001) and size of cervical nodes (P = 0.01) significantly contributed to the occurrence of RPLN metastasis. Conclusion: The locoregional spread of HPC occurs via certain routes. It is potentially unnecessary to routinely and prophylactically irradiate the nasopharynx and skull base. Patients with early stage HPC should receive bilateral cervical prophylactic irradiation. The decision regarding the administration of prophylactic irradiation to the level VI and RPLN areas should be according to the relative risk factors.