Systemic Inflammatory Indices and Free Flap Outcomes in Oral Cavity Cancer Reconstruction: A Multicenter Cohort Study

BACKGROUND: Free flap reconstruction is central to oral cavity cancer (OCC) management; however, flap-related complications remain clinically consequential. Current perioperative strategies are largely reactive, and reliable preoperative markers identifying patients at increased risk of flap-related complications are lacking. This study aimed to evaluate the association between preoperative systemic inflammatory indices and free flap-related complications in OCC reconstruction. METHODS: We performed a retrospective, multicenter cohort study using the Chang Gung Research Database, including patients undergoing ablative surgery with free flap reconstruction (2002-2022). Preoperative laboratory data obtained within 30 days before surgery were used to calculate the neutrophil-to-lymphocyte ratio (NLR), platelet-to-lymphocyte ratio (PLR), and lymphocyte-to-monocyte ratio (LMR). The primary outcome was flap-related complications, defined as surgical re-exploration within 30 days. Multivariable logistic regression models were used to estimate adjusted odds ratios (aORs) with prespecified clinical covariates. RESULTS: Among 7444 patients, 10.9% required re-exploration, including 3.5% with total flap loss and 7.3% with flap revision. Elevated NLR (≥ 4.0) was associated with higher complication risk (aOR = 1.36; 95% CI = 1.15-1.60; p = 0.001), whereas higher LMR (≥ 4.36) was protective (aOR = 0.68; 95% CI = 0.58-0.81; p < 0.001). These associations were consistent across both flap revision and total flap failure. CONCLUSIONS: Preoperative NLR and LMR provide incremental risk stratification beyond established clinical factors and may serve as clinically accessible markers of free flap-related risk in OCC reconstruction. These findings support a more refined, risk-adapted approach to perioperative assessment, although prospective validation is required.