This study aims to assess the survival rate of oral squamous cell carcinoma (OSCC) patients following immediate mandibular reconstruction with vascularized fibula flap (VFF) and to identify risk factors influencing the overall survival rate and postoperative outcomes.

Patients suitable for the inclusion criterion diagnosed and treated between January 1996 till June 2019 for OSCC were retrospectively reviewed (n = 74). Potential risk factors and postoperative outcomes were recorded and analyzed.

The overall cumulative survival rate of patients was 0.52 at the end of 5th year. Overall, advanced pN stage (p = 0.0422), poor tumor differentiation (p < 0.0001), positive/close surgical margins (p = 0.0209), vascular invasion (p = 0.0395), perineural invasion (p = 0.0022) and tumor recurrence (p = 0.0232) were significantly related to a decreased cumulative survival. Tumor recurrence was significantly correlated with involvement of positive/close surgical margins, moderate (p = 0.0488), poor-differentiated tumors (p = 0.202), extracapsular spread (p = 0.0465), computer-assisted surgery (p = 0.0014) and early complications (p = 0.0224). Pain was significantly associated with the extracapsular spread (p = 0.0353) and early complications (p = 0.0127).

The five-year survival rate of advanced OSCC patients after segmental mandibulectomy with fibula free-flap reconstruction was 52.4%. Clinical/pathological risk factors such as the pN stage, tumor differentiation, surgical margins, vascular invasion, perineural invasion, tumor recurrence significantly influenced the overall cumulative survival rate.