The volume of retropharyngeal nodes predicts distant metastasis in patients with advanced nasopharyngeal carcinoma.

We investigated the effect of retropharyngeal nodal volumes (RNV) on distant metastasis in patients with advanced nasopharyngeal carcinoma (NPC). From February 2000 to June 2006, a total of 181 patients with biopsy-proven NPC, no distant metastasis, and available pre-treatment magnetic resonance imaging (MRI) were retrospectively reviewed. Most of the patients (95.6%) had stage III/IV diseases. The contour of retropharyngeal nodes ≥5mm was delineated on the axial slides of pre-treatment T2-weighted MRI without contrast enhancement. The RNV was calculated by the Eclipse™ treatment planning software. The primary end-points were subsequent distant failure rates and distant metastasis failure-free survival (DMFFS). The pre-treatment RNV in patients who developed distant failure was higher than in those without distant failure (P=0.0536). The distant failure rates between the patients with RNV > and ≤4.68cm(3) were 33.3% and 16.0%, respectively (P=0.0112). The rates of 7-year DMFFS in patients with RNV > and ≤4.68cm(3) were 66.4% and 83.5%, respectively (P=0.0043). Multivariate Cox analysis showed N-stage (P<0.001), gender (P=0.026), and RNV (P=0.088) were important predictors for DMFFS. We conclude that the RNV measured by MRI is a potential predictor of distant metastasis in patients with advanced NPC.