Clinical outcomes of patients with oral cavity squamous cell carcinoma and retropharyngeal lymph node metastasis identified by FDG PET/CT.

Purpose: Retropharyngeal lymph node (RPLN) metastasis is an uncommon finding in patients with oral cavity squamous carcinoma (OSCC). We sought to investigate the clinical outcomes, clinicopathological characteristics, and the priority of treatment with curative intent in OSCC patients with RPLN involvement.
Methods and Materials: Between January 2007 and January 2011, we identified 36 patients with primary RPLN metastases (n = 10) or RPLN relapse (n = 26). The follow-up continued until June 2013. Disease-specific survival (DSS), disease-free survival (DFS), and the potential benefits of salvage therapy served as the main outcome measures.
Results: The 2-year DSS and DFS rates of untreated patients with RPLN involvement were 20% and 24%, respectively. Level IV/V neck lymph node involvement was an adverse prognostic factor for DSS (P = 0.048) and DFS (P = 0.018). All of the patients presenting with neck lymph node involvement at level IV/V died within 6 months. Among patients who were treated for RPLN relapse, the 2-year DSS and DFS rates from the relapse day were 12.8% and 9.6%, respectively. Concomitant contralateral neck lymph node metastases (N2c) were associated with lower 2-year DSS (P = 0.005) and DFS (P = 0.011) rates. Moreover, five (55%) of the nine patients with recurrent disease in the contralateral RPLN had distant metastases within 6 months. Salvage therapy yielded the maximum survival benefit in patients without N2c disease and ipsilateral RPLN involvement alone (P = 0.005).
Conclusion: OSCC patients with RPLN involvement have poor outcomes. The risk factor for definitive treatment in OSCC patients with FDG PET/CT defined RPLN disease in primary disease was neck lymph node involvement at level IV/V and N2c and/or contralateral RPLN disease in recurrent disease. Treatment efforts with curative intent should be tailored according to individual risk factors.