Top Line: Is it safe to omit elective coverage of the low neck in patients with N0-N1 nasopharyngeal carcinoma?
The Study: Most patients (~70%) with NPC have cervical lymph node metastases. A recent large retrospective study described patterns of nodal involvement for NPC with >80% of nodal metastases involving the retropharyngeal and level IIB nodes. Metastases to less commonly involved nodal regions in the lower neck typically occurred in the setting of mets to adjacent nodal regions. In this phase 3 trial, 449 patients receiving definitive chemoradiation for N0-N1 nonkeratinizing NPC at 3 Chinese centers were randomized to elective coverage of the entire neck or the upper neck only. The goal was to determine if reducing the volume of elective coverage would reduce toxicity without increasing relapse-free survival. Treatment plans used a 3 volume approach targeting gross disease (66-70 Gy), high risk CTV (60-62 Gy), and low risk elective neck (54-56 Gy) in 30-33 fractions. Standard elective neck coverage included levels II-VB. In the experimental arm, levels IV and VB were omitted either unilaterally or bilaterally if there were no cervical node metastases on that side of the neck (retropharyngeal mets were allowed). At 3 years, there was no difference in the rate of relapse (3% in both arms) or the rate of relapse-free survival with omission of lower neck irradiation (97.7% v 96.3%). There were also no differences in overall survival, distant metastasis free survival, or local and regional relapse-free survival. There were also no differences in outcomes when analyzed according to pretreatment plasma EBV titer. While there were no major differences in acute toxicity, omitting the low cN0 neck reduced late skin toxicity (14% v 25%), dysphagia (17% v 32%), and neck fibrosis (23% v 40%).
TBL: Omitting levels IV and VB from the cN0 elective neck volume for patients with N0-N1 NPC reduces late toxicity (but not acute toxicity) while maintaining excellent relapse-free survival. | Tang, Lancet Oncol 2022