Lymph node ratio and failure in HNSCCLymph node ratio relationship to regional failure and distant metastases in oral cavity cancer

BackgroundWe aimed to investigate the impact of lymph node ratio (LNR, number of positive nodes/total number of excised nodes) on regional-only-failure, distant-only-failure and overall survival (OS) in oral squamous cell carcinoma (OSCC).MethodsRetrospective review of pN0-2 OSCC-patients (1994-2012) treated with curative-surgery with neck dissection ± postoperative radiotherapy (PORT) ± concurrent chemotherapy. LNR was subjected to multivariable analysis (MVA) of regional-only-failure, distant-only-failure and OS.ResultsOverall 914 patients were identified; median follow-up: 51 months (1-189); pN0: 482 (52.7%), pN1: 128 (14%), pN2a: 6 (0.7%); pN2b: 225 (24.6%); pN2c: 73 (8%); median number of dissected nodes: 36 (6-125); median number of pN+: 2 (1-49); median LNR for pN+ patients: 6%; extranodal extension: 187 (20.5%). Bilateral neck dissection: 368 (40.3%); PORT: 452 (49.5%); and concurrent chemotherapy: 80 (8.8%). High grade, lymphovascular invasion perineural invasion and pT3-4 were associated with high LNR. On MVA, LNR was associated with regional-only-failure (HR = 1.06; 95%CI: 1.04-1.08; p < 0.001), distant-only-failure (HR = 1.03; 95%CI: 1.02-1.05; p = 0.004) and lower OS (HR = 1.03; 95%CI: 1.02-1.05; p < 0.001). Similarly, in pN2-subgroup: LNR was associated with regional-only-failure (HR = 1.04; 95%CI: 1.02-1.06; p < 0.001), distant-only-failure (HR = 1.03; 95%CI: 1.01-1.06; p = 0.045) and lower OS (HR = 1.03; 95%CI: 1.02-1.04; p < 0.001).ConclusionHigh LNR is associated with higher regional-only-failure/distant-only-failure and lower OS. LNR should be assessed in future prospective trials for selection of adjuvant therapy.