Pattern of Mandibular Bone Invasion as a Prognostic Factor

Background/Objectives: Mandibular bone invasion is a common and clinically relevant feature of OSCC, particularly in tumors of the lower alveolus, floor of mouth, and retromolar trigone. The prognostic value of the pattern of invasion-rather than its mere presence-remains insufficiently defined. Therefore, we evaluated the prognostic relevance of erosive vs. infiltrative mandibular invasion and the diagnostic reliability of preoperative CT. Methods: This retrospective, single-center observational cohort study included 83 patients with OSCC involving or adjacent to the mandible who underwent surgical resection at the Department of Oral and Maxillofacial Surgery, University Hospital Olomouc (2008-2018). Bone invasion type was classified histopathologically as erosive or infiltrative. Survival outcomes were analyzed using Kaplan-Meier and Cox regression methods. Correlation between radiologic and histologic findings was assessed using Cohen's kappa statistics. Results: Mandibular invasion was confirmed in 50.6% of cases, of which roughly two-thirds were infiltrative. DSS differed across invasion groups (log-rank p = 0.012): infiltrative had a median DSS of 14.5 months (95% CI 0.0-32.8), no invasion had 54.2 months (CI not estimable), while erosive did not reach the median (fewer than half experienced the event). In the adjusted model (covariates: invasion type, ENE, grade, margins), infiltrative vs. no invasion was associated with worse DSS (aHR 1.93, 95% CI 1.02-3.64; p = 0.042); for OS, erosive vs. no invasion showed a protective association (aHR 0.39, 95% CI 0.16-0.96; p = 0.041). Positive/close margins were independently adverse across endpoints (e.g., DSS aHR 3.30, 95% CI 1.74-6.22). CT-histology agreement for bone invasion was κ = 0.45, indicating moderate agreement. Conclusions: In this retrospective single-center cohort, the pattern of mandibular bone invasion was associated with survival: infiltrative invasion aligned with worse outcomes, whereas erosive behaved similarly to no invasion, particularly for OS. Prospective, multicenter validation is warranted before routine incorporation into risk stratification or treatment selection.