Preoperative serum interleukin-6 level in head and neck cancer reflects systemic inflammatory response and is a predictor of postoperative prognosis.

BACKGROUND The outcome of head and neck cancer has improved in recent years but survival is not yet satisfactory. Interleukin (IL)-6 is a representative inflammatory cytokine and inducer of systemic inflammatory response. It is not known whether preoperative serum level of IL-6 is a prognostic factor in head and neck cancer surgery. METHODS We studied 181 consecutive patients who underwent head and neck surgery with free tissue transfer reconstruction (HNS-FTTR) between September 2016 and December 2020. Whether preoperative serum IL-6 level was a prognostic risk factor was retrospectively investigated by univariate and multivariate analyses. We also investigated the association between preoperative IL-6 level and representative systemic inflammatory response markers. RESULTS The preoperative IL-6 ≥ 8 pg/mL group had a significantly worse prognosis than the preoperative IL-6 < 8 pg/mL group (overall survival [OS]: hazard ratio [HR] 3.098, P = 0.0006; disease-specific survival [DSS]: HR 3.335, P = 0.0008). In multivariate analysis, IL-6 ≥ 8 pg/mL and age ≥ 70 years were independent poor prognostic factors for OS (HR 1.860, P = 0.0435 and HR 1.883, P = 0.0233, respectively). The only independent poor prognostic factor for DSS was IL-6 ≥ 8 pg/mL (HR 2.052, P = 0.0329). Serum albumin was significantly lower and serum C-reactive protein and neutrophil-to-lymphocyte ratio were significantly higher in the IL-6 ≥ 8 pg/mL group than in the IL-6 < 8 pg/mL group (all P < 0.0001). CONCLUSIONS Preoperative serum IL-6 level is an independent poor prognostic factor for both OS and DSS after HNS-FTTR, reflecting the degree of preoperative systemic inflammatory response.