Prognostic and predictive value of IGFBP-6 in head and neck squamous cell carcinoma

The aim of this study was to assess insulin-like growth factor binding protein-6 (IGFBP-6) expression, and its potential value as a prognostic indicator of survival in patients with head and neck cancer (HNC). Quantitative realtime polymerase chain reaction (qRT-PCR) and immunohistochemistry analyses were used to determine IGFBP-6 mRNA and protein expression, respectively, in HNC. The correlations between IGFBP-6 expression levels and clinical characteristics or prognoses were determined via statistical analyses. IGFBP-6 mRNA and protein levels were significantly higher in HNC tissues than in normal adjacent tissues (P<0.000 1). High IGFBP-6 expression in cancer tissues was significantly associated with sex (P=0.013), tobacco consumption (P=0.021), tumor location (P=0.001), histopathological grade (P=0.030), T stage(P=0.04), and tumor classification. IGFBP-6 expression in buccal squamous cell carcinoma (BSCC) tissues was correlated with laryngeal squamous cell carcinoma (LSCC) development (P=0.001) but not tongue squamous cell carcinoma (TSCC) development (P=0.355). High IGFBP-6 expression (P=0.001), histopathological grade (P=0.020), T stage (P=0.007), lymph node metastasis (P=0.001), and pTNM stage (P=0.001) were identified as significant prognostic factors for survival. Kaplan-Meier survival curves demonstrated that patients with high IGFBP-6 levels or stage Ⅲ + Ⅳ cancer exhibited significantly shorter survival times than patients with low IGFBP-6 levels or stage Ⅰ + Ⅱ disease. Our findings provide the first evidence that high IGFBP-6 expression is associated with poor prognosis in HNC.