RANK and RANKL expression lack prognostic significance in squamous cell carcinomas with mandibular invasion

Objectives: Mandible management is important in the surgical treatment of oral squamous cell carcinomas (OSCCs) that are proximal to or that have invaded the mandible. This retrospective study investigated the prognostic impact of invasion. Materials and methods: We analysed 58 consecutive OSCC patients with clinical or radiological signs of bone infiltration that underwent marginal mandibular resection (n = 35) or segmental mandibular resection (n = 23) between 2010 and 2014. The expression of RANK/RANKL was analysed in the tested samples. These molecules are part of the signalling pathway that regulates osteoclast activation and differentiation. Results: Patients with segmental mandibulectomy and local recurrence had a worse prognosis (p = 0.084 and p = 0.071). Tumour size was an independent significant predictor of reduced survival (p = 0.048), but bone invasion was not (p = 0.950). Immunoarray analysis detected no RANKL expression, but 21 patients expressed RANK on the surface of the tumour. Conclusions: In this cohort, bone invasion was not an independent prognostic factor when covariates such as tumour size were taken into consideration. These results indicate that bone invasion has a minor prognostic impact on the survival of patients with OSCC. Moreover, the correlation between RANK and RANKL expression and mandible invasion by OSCC showed that their expression did not have prognostic significance.