Lymph node-to-primary tumor standardized uptake value ratio on PET predicts distant metastasis in nasopharyngeal carcinoma.

OBJECTIVES To investigate the prognostic value of the relative maximum standardized uptake value (SUV) ratio between neck lymph node and primary tumor (NTR) measured by pretreatment 18F-FDG PET in patients with nasopharyngeal carcinoma (NPC). MATERIALS AND METHODS We retrospectively reviewed patients with non-disseminated NPC who underwent PET scans before radical intensity-modulated radiotherapy (IMRT). Receiver operating characteristic analysis was performed to identify the optimal cut-off value for NTR. The prognostic value of NTR for distant metastasis-free survival (DMFS) was evaluated using Kaplan-Meier method for survival analyses and Cox regression for multivariable analysis. RESULTS Among the 437 eligible patients, the median follow-up time was 62.9 (range, 2.1-113.0) months. Patients with high NTR (NTR > 0.9181) experienced significantly worse DMFS (5-year 80.5% vs. 91.6%, P < 0.001). In the subgroup analysis, we found that patients with high NTR had significantly lower DMFS in T1-2 category (5-year 86.1% vs. 98.1%, P = 0.002), T3-4 category (5-year 71.5% vs. 86.2%, P = 0.010), N2-3 category (5-year 75.3% vs. 86.2%, P = 0.048), and stage IVA-B (5-year 69.8% vs. 85.4%, P = 0.012). Multivariable analysis showed that NTR was an independent prognostic factor for DMFS (HR 2.20, 95% CI 1.20-4.03, P = 0.011). CONCLUSION Pretreatment NTR is an easily accessible but potential prognosticator for DMFS in NPC patients treated by IMRT, which may help in providing more personalized treatment or designing future clinical trials.