Karthik N Rao, Teertha Shetty, Shanthi Velusamy, Prajwal Dange, Sreeram Mp, B S Srinath
NDSI correlate with adverse pathology and early mortality. However, the association between NDSI and ENE is not fully independent of pathological N-stage, and reproducibility, independent prognostic value, and cutoff stability require external validation before clinical use.
BACKGROUND: Cervical nodal metastasis critically influences prognosis in oral squamous cell carcinoma (OSCC), yet current staging does not quantify the degree of metastatic replacement within lymph nodes. This study evaluated morphometric index Node Deposit Size Index (NDSI) to assess their association with pathological aggressiveness and survival.
METHODS: An ambispective cohort of 104 surgically treated, node-positive OSCC patients was analysed. Maximum metastatic deposit diameter and lymph node diameter were measured on routine H&E slides. NDSI correlated with clinicopathological variables, extranodal extension (ENE), lymph node density (LND), and survival using non-parametric tests, Spearman correlation, Kaplan-Meier analysis, and ROC curves.
RESULTS: ENE-positive nodes demonstrated higher NDSI than ENE-negative nodes (86.9% vs 43.8%; p < 0.001). NDSI increased across pathological nodal stage (pN), from 31.9% in pN1 to 87.8% in pN3b (p < 0.001), and across overall stage, reaching 87.9% in Stage IVB (p < 0.001). Higher NDSI was associated with lymphovascular invasion (LVI) (72.0% vs 45.4%; p < 0.001) and perineural invasion (69.5% vs 50.7%; p = 0.024). NDSI correlated with LND (Spearman ρ=0.43, p < 0.001). ROC analysis identified an NDSI cutoff of 73.3% for predicting ENE (AUC = 0.854; not internally validated) and a cutoff of 60% for predicting 1-year mortality (AUC = 0.708; not internally validated). On multivariable linear regression (R² = 0.524), LVI and pN (pN2a, pN2b, and pN3b) were independently associated with higher NDSI, whereas the remaining clinicopathological variables were not independently significant.
CONCLUSION: NDSI correlate with adverse pathology and early mortality. However, the association between NDSI and ENE is not fully independent of pathological N-stage, and reproducibility, independent prognostic value, and cutoff stability require external validation before clinical use.