Lymph node metastasis and prognostic value of NPC based on the UICC lymph node staging for cervical lymph node levels.

Abstract

e18136 Background: Nasopharyngeal carcinoma (NPC) is the most common cancer originating in the nasopharynx. The neck lymph node (LN) metastasis is very common in NPC; it plays an important role in tumor staging which is guide the choice of treatment. Methods: 324 patients were pathologically diagnosed as non-metastatic NPC from Jan. 2005 to Dec.2010 were recruited retrospectively to analysis. All of them treated with standard IMRT. The clinical data including CT/MRI images, followed up were collected, while the OS, DFS, DMFS and RRFS were calculated. Survival analysis was performed by Kaplan-Meier method, and COX regression model was used for multivariate analysis. Results: The median follow-up time was 66 months (6-134 months). The 5-year LRFS,NRFS,DMFS,DFS and OS was 93.5%, 97.4%, 73.4%, 69.1% and 79.2%,respectively. The most common metastatic LN levels were II level 83.9%, retropharyngeal LN level 69.1%, followed by III level 16.9%, Va level 8% ,IV level 5.2% and Vb level 4%. All the retropharyngeal LNs were involved in the lateral group while no medial ones was found. In cervical LN, necrosis was involved in 40.0% patients with positive nodes and extracapsular invasion was noted in 58.6%. Bilateral positive LN was involved in 66.5%, and there was 11.4% in the lower cervical region. Univariate analysis showed that LN diameter greater than 3 cm, extracapsular invasion, LN necrosis and LN laterality are independent prognostic factors for DMFS and DFS (P < 0.05). T staging and N staging were independent prognostic factors for the DMFS (P = 0.024, 0.012, respectively). Lower cervical involvement had no significant effect on DMFS and DFS. Multivariate analysis showed that T staging, extracapsular invasion and laterality were independent prognostic factors (P < 0.05) for DFS, and extracapsular invasion was an independent prognostic factor (P = 0.048) for DMFS. Conclusions: Our results suggested II level and retropharyngeal LN have the highest metastasis rate. All retropharyngeal LN were involved in the lateral group but not medial one. Laterality, maximum diameter and necrosis are independent prognostic factors for DFS and DMFS. The involvement of the lower cervical region had no significant effect on DFS and DMFS.