Tumor budding to investigate local invasion, metastasis and prognosis in temporal bone squamous cell carcinoma.

Background: Few studies have tried to go beyond the conventional clinic-pathological prognostic factors investigating the molecular markers involved in the biology of temporal bone squamous cell carcinoma (TBSSC). Tumor budding represents a very aggressive subpopulation of cancer cells and demonstrates the heterogeneity of cancer cells residing in different locations within tumors. The main aim of this exploratory study was to investigate the role of tumor budding in primary TBSCC prognosis. We also analyzed the association between TBSCC tumor budding and: (i) loco-regional aggressiveness evaluated according to the revised Pittsburgh staging system, (ii) tumor infiltrating lymphocytes, lymphovascular invasion (LVSI), perineural invasion, pattern of invasion, and type of stroma. Methods: Thirty-two TBSCCs treated surgically were considered. The three-tier grading system recommended by the International Tumor Budding Consensus Conference was used first on TBSCC. Results: Advanced (T3–4) TBSCC was related with high risk intra-tumoral budding (ITB) at two-tier risk grading (p = 0.0361). N + status was associated with intermediate/high budding (Bd2–3) at three-tier risk grading for peri-tumoral budding (PTB) (p = 0.0382). Disease-free survival (DFS) was related with T-stage (p = 0.0406), Nstatus (p < 0.0001), PTB two-tier risk grading (p = 0.0463), LVSI (p < 0.0001). Overall survival (OS) was associated with N-status (p = 0.0167), PTB absolute count (p = 0.0341), PTB three-tier risk grading (p = 0.0359), PTB two-tier risk grading (p = 0.0132), and LVSI (p = 0.0004). At the multivariate analysis, DFS was related with N-status (p = 0.0147) and LVSI (p < 0.0001), while OS resulted associated only with LVSI (p = 0.0144). Conclusions: Our preliminary findings suggest that tumor budding in TBSCC, regardless of its localization (the main tumor body [ITB] or invasive front [PTB]) may be a reliable predictor of neck lymph node metastasis and poor prognosis. Tumor budding and LVI could be predictive markers for precise treatment in TBSCC. Further investigations on larger prospective series should be designed to confirm this evidence both in post-operative specimens and in preoperative biopsies.