Lymph node ratio and patterns of recurrence in oral squamous cell carcinoma treated with surgery and adjuvant concurrent chemoradiotherapy.

e18084 Background: Despite curative surgery and adjuvant concurrent chemoradiotherapy (CCRT), a subset of patients with oral squamous cell carcinoma (OSCC) develop disease recurrence. Conventional nodal staging may not adequately reflect postoperative nodal burden or residual risk. Lymph node ratio (LNR), defined as the proportion of metastatic to examined lymph nodes, may better characterize recurrence patterns following standard multimodality treatment. Methods: This retrospective clinical study evaluated 1,783 patients with OSCC treated with surgery and adjuvant CCRT between 2019 and 2023. Patients who developed recurrence during follow-up and had complete pathological and clinical data were analyzed (n=119; 6.7%). LNR was calculated as the number of positive lymph nodes divided by total nodes retrieved and categorized as ≤0.10 or >0.10. Recurrence pattern and time to recurrence were assessed. Results: Median lymph nodes retrieved was 29 (range 17–39), with a median of 1 positive node (range 1–9). Median LNR was 0.05 (range 0.02–0.52); 89 patients (74.8%) had LNR ≤0.10 and 30 (25.2%) had LNR >0.10. Recurrence was predominantly locoregional, occurring in 108 patients (90.8%), while distant recurrence occurred in 9 patients (7.6%) and combined locoregional and distant failure in 1 patient (0.8%). Median time to recurrence was 19 months. A higher LNR was associated with a greater proportion of non-locoregional failure. Conclusions: In a large, uniformly treated OSCC cohort, recurrence after surgery and adjuvant CCRT is infrequent but overwhelmingly locoregional. Postoperative lymph node ratio provides a pragmatic measure of nodal burden and identifies patients with a higher likelihood of non-locoregional failure despite standard therapy. LNR may complement conventional nodal staging to inform post-treatment risk stratification and surveillance strategies. Clinicopathologic characteristics and recurrence patterns by lymph node ratio (LNR). Variable Overall (n = 119) LNR ≤0.10 (n = 89) LNR >0.10 (n = 30) Median lymph nodes retrieved, n (range) 29 (17–39) 28 (17–39) 31 (18–38) Median positive lymph nodes, n (range) 1 (1–9) 1 (1–3) 4 (2–9) Median LNR (range) 0.05 (0.02–0.52) 0.04 (0.02–0.10) 0.21 (0.11–0.52) Locoregional recurrence, n (%) 108 (90.8) 83 (93.3) 25 (83.3) Distant recurrence, n (%) 9 (7.6) 5 (5.6) 4 (13.3) Combined locoregional + distant recurrence, n (%) 1 (0.8) 0 1 (3.3) Median time to recurrence, months 19 21 14