Locoregional recurrence patterns in surgically treated stage III and IV oral squamous cell carcinoma: a prospective observational study.

Background: Advanced oral squamous cell carcinoma demonstrates high locoregional recurrence despite multimodal therapy. This study identified clinical and pathological predictors of recurrence in surgically treated stage III-IV OSCC.

Methods: This prospective observational study analyzed 260 patients with stage III-IV OSCC treated at a tertiary cancer center (2019-2021). Clinicopathological parameters including tumor staging, lymph node ratio, differentiation, margins, depth of invasion, extracapsular extension, lymphovascular invasion, perineural invasion and treatment factors were evaluated. Multivariate Cox regression identified independent predictors. ROC curve analysis determined optimal cutoffs.

Results: Locoregional recurrence occurred in 44/260 patients (16.92%). Univariate analysis revealed significant associations with LNR (p < 0.00001), ECE (p < 0.00001), LVI (p = 0.003), positive lymph nodes (p = 0.001), radiotherapy completion (p = 0.009), and surgery to radiation interval (p = 0.0002). Multivariate analysis identified three independent predictors: PNI (OR 18.42, 95% CI 5.43-62.46, p < 0.01), ECE (OR 8.17, 95% CI 1.51-44.33, p = 0.01), and positive node count (OR 1.64, 95% CI 1.21-2.22, p < 0.01). ROC analysis established ≥ 2 positive nodes as optimal cutoff (AUC = 0.844), stratifying patients into low-risk (< 2 nodes: 3.4% recurrence) and high-risk (≥ 2 nodes: 44.7% recurrence) groups. T-stage, margins, depth of invasion, and differentiation showed no significant association.

Conclusions: PNI, ECE, and positive lymph node count independently predict locoregional recurrence in advanced OSCC. Our risk stratification model incorporating these factors enables personalized surveillance and adjuvant therapy intensification. Radiotherapy should commence within six weeks of surgery for optimal outcomes.