Multi-center retrospective study of the prognosis and treatment outcomes of Japanese oral squamous cell carcinoma patients with single lymph node metastasis and extra nodal extension

BackgroundOral squamous cell carcinoma (OSCC) containing single lymph node metastasis (pN1) with extra nodal extension (ENE) is a rare clinical situation. Therefore, it is unclear whether pN1 with ENE is at high risk of recurrence among the OSCC population, or whether postoperative radiotherapy (RT)/concomitant chemoradiotherapy (CCRT) is effective in these cases. ObjectivesThe purpose of this retrospective study was to investigate the prognosis and compare between no postoperative therapy and postoperative RT/CCRT in pN1 with ENE OSCC patients. MethodsClinicopathological data and treatment modalities were investigated. The evaluated endpoints were overall survival (OS) and type of recurrence. ResultsThe 3-year cumulative OS rates for the pN1 only, multiple lymph node metastasis (MLM) only, ENE+MLM, and ENE+pN1 groups were 77.2%, 66.8%, 43.3%, and 66.6%, respectively. In the ENE+pN1 group, the most common cause of death in the surgery only group was from regional failure. The surgery+RT/CCRT group was associated with better disease-specific survival and OS rates than the surgery only groups (P<0.05). ConclusionsThe prognosis of ENE+pN1 was not as poor as that of ENE+MLM, although both these groups feature ENE. Adjuvant therapy (RT/CCRT) after surgery is recommend for cases of ENE+pN1.