Treatment outcome of nasopharyngeal carcinoma with retropharyngeal lymph nodes metastasis only and the feasibility of elective neck irradiation

SummaryObjectiveTo investigate the outcome of nasopharyngeal carcinoma (NPC) with retropharyngeal lymph nodes (RLNs) metastasis only and evaluate the feasibility of elective neck irradiation.Materials and methodsThis is a retrospective study of 119 newly diagnosed non-metastatic NPC patients with RLNs metastasis only. All of them received definitive radiotherapy. Eighty nine patients received elective neck irradiation to levels II, III, VA and the rest received whole neck irradiation, including levels II–V.ResultsThe median follow-up was 36.6 months. The 5-year local recurrence-free survival (LFS), nodal recurrence-free survival (NFS), distant metastasis-free survival (DMFS) and overall survival (OS) was 81.4%, 92.7%, 91.8%, and 93.6%, respectively. Four patients developed nodal relapse and only one was out-of-field relapse. No significant difference of nodal recurrence was observed between elective neck irradiation and whole neck irradiation. IMRT or three-dimensional conformal radiotherapy (3D-CRT) showed a trend of improving regional control, compared with conventional two-dimensional radiotherapy (2D-RT) (p = 0.074). In 2D-RT, a higher dose (>5600 cGy) to the upper neck showed a benefit of regional control(p = 0.006). Multivariate analysis demonstrated that only the dose of upper neck was an independent prognostic factor of NFS.ConclusionsElective irradiation to levels II, III, VA was not inferior to whole neck irradiation for NPC patients with RLNs metastasis only. However, more evidences are needed to confirm the result. IMRT showed a trend of improving regional control. A higher dose of prophylactic radiation may be required for upper neck region in patients with RLNs metastasis.