Management of retropharyngeal lymph node metastasis in oral cancer

Objectives: Retropharyngeal lymph node (RPLN) metastasis is extremely rare, and prognosis is significantly poor in oral cancer. We retrospectively examined the management of RPLN metastases in oral cancer. Materials and methods: A total of 1247 patients with oral cancer were treated at our department from January 2002 and December 2016. Among these patients, 374 (30%) had histologically positive lymph node metastases. Of these, 15 patients (1.2%) were diagnosed with RPLN metastases. We evaluated the diagnostic period, size, recurrence pattern, laterality, treatment, and therapeutic outcomes. The Kaplan-Meier method was used to determine overall survival (OS) among the RPLN metastasis group, cervical lymph node (CLN) metastases group, and treatment methods group for RPLN metastases. Results: One patient had RPLN involvement at the initial treatment, and RPLN involvement in other patients was found subsequently. The mean duration in confirming RPLN metastases was 228 days (range, 50-867 days). Surgical therapy was performed in 5 patients, chemoradiotherapy in 7 patients, and best supported care (BSC) in 3 patients. The cumulative 5-year OS rate for the RPLN metastasis group (n = 15) was 38.1%, compared with the rate of 71.3% for the CLN group (n = 359). Regarding the therapeutic approach for RPLN metastases, OS rates were 80.0% (n = 5) in the surgical therapy group, 28.6% (n = 7) in the chemoradiotherapy group, and 0% (n = 3) in the BSC group. Conclusion: Early detection and surgical treatment of RPLN metastases are associated with increased survival rate in oral cancer.