Development and validation of a practical score to predict 3-year distant metastatic free survival in nasopharyngeal carcinoma incorporating the number of lymph node regions

by Thitiporn Jaruthien, Chawalit Lertbutsayanukul, Nutchawan Jittapiromsak, Aniwat Sriyook, Prapasri Kulalert, Pichaya Tantiyavarong, Sarin Kitpanit, Danita Kannarunimit, Chakkapong Chakkabat, Anussara Prayongrat

Introduction

The improvement in diagnosis and treatment for nasopharyngeal carcinoma (NPC) has shifted the pattern of failure toward distant metastasis. This study aimed to develop a simplified prognostic scoring model to predict distant metastatic free survival (DMFS) for NPC patients.

Materials and methods

Patients with non-metastatic NPC were identified from a retrospective cohort diagnosed between 2010 and 2018. Flexible parametric survival analysis was used to identify potential predictors for DMFS and establish a scoring model. The prognostic accuracy between the 8^th AJCC system and the scoring model was compared using Harrell’s C-index.

Results

Of the total 393 patients, the median follow-up time was 85 months. The 3-year DMFS rate was 83.3%. Gender, T-stage, pre-EBV (cut-off 2300 copies/ml), and the number of metastatic lymph node regions were identified as independent risk factors for distant metastasis and were included in the final scoring model. Our established model achieved a high C-index in predicting DMFS (0.79) and was well-calibrated. The score divided patients into two categories: low-risk (score 0–4) and high-risk (score 5–7), corresponding with the predicted 3-year DMFS of 96% and 64.5%, respectively.

Conclusions

A feasible and applicative prognostic score was established and validated to discriminate NPC patients into low- and high-risk groups.