Posterior cervical lymph node metastasis as the valuable prognostic factor for stage IVA/IVB nasopharyngeal carcinoma treated with induction chemotherapy followed by concurrent chemo-radiotherapy

Introduction/aim: To evaluate the prognostic properties of retropharyngeal lymph node (RP), posterior cervical lymph node (PCN), and supraclavicular lymph node (SPC), in stage IVA/IVB nasopharyngeal carcinoma (NPC) patients in setting of induction chemotherapy.

Methods: We performed a retrospective study including 43 patients with stage IVA/IVB NPC (7^th AJCC) treated with induction chemotherapy followed by concurrent chemo-radiotherapy. We analyzed prognosis with the multivariate Cox regression model and p-value from the Wald’s test, using the backward elimination method (by likelihood ratio test and percent change of coefficient factors).

Result: Overall, 24 patients (55.8%) were in stage IVA and 19 (44.2%) in stage IVB. After a median follow-up time of 30 months, the 2-year overall survival (OS) was 79.1%, while the 2-year progression free survival (PFS) and distant metastasis free survival (DMFS) were 59.8% and 69.1%, respectively. In multivariate analysis for predicting DMFS, SPC involvement was not statistically significant (HR 3.39; 95% CI 0.76-15.07; p=0.1), whereas RP involvement was statistically significant (HR 5.81; 95% CI 1.08-31.16; p=0.04). Moreover, and more importantly, PCN involvement was the only nodal factor to predict all of DMFS, PFS, and OS (respectively HR 5.57, 95% CI 1.12-27.71, p=0.036; HR 16.05, 95% CI 1.93-133.65, p=0.01; and HR 28.02, 95% CI 2.74-286.22, p=0.005).

Discussion: PCN involvement is the only independent prognostic factor of stage IVA/IVB NPC patients treated by induction chemotherapy that predicts DMFS and turns this effect to PFS and OS. PCN involvement is a highly accurate predictor for failure of conventional chemo-radiotherapy. Therefore, patients with PCN involvement should be defined at high-risk, as to be investigated for a new staging system.