Radiotherapeutic factors related to the control of cervical lymph node metastases in patients with oro- and hypopharyngeal carcinoma treated with chemoradiotherapy followed by planned neck dissection

Abstract

To clarify radiotherapeutic factors related to the control of cervical lymph node metastases, we retrospectively reviewed 29 patients with N2-3 oro- and hypopharyngeal squamous cell carcinoma treated with chemoradiotherapy followed by planned neck dissection between April 2004 and March 2008. Pretreatment assessment of all patients revealed cervical metastases in a total of 63 neck levels. Planning target volume (PTV) was defined as lymph node metastases by neck level with a 5-mm margin, and a dose-volume histogram (DVH) was used to evaluate the maximum (PTV max), minimum (PTV min) and mean radiation dose to the PTV (PTV mean). Overall, 59% of the patients attained a pathologic complete response (pCR) in the neck. Evidence of residual pathologic tumor by neck level was found most commonly in Level V and retropharyngeal lymph nodes. On univariate analysis, primary site (oropharynx) and the effect of induction chemotherapy (partial response) were significant predictors of a neck disease specimen with negative pathology. PTV max and PTV mean in Level V were found to be significantly lower than those in Levels II and III. Furthermore, there was a significant association between radiation dose and pathologic status on the neck. Our data thus suggested that excellent dose coverage for cervical lymph nodes might lead to better regional control.