Expression of Y-box-binding protein YB-1 allows stratification into long-and short-term survivors of head and neck cancer patients

Background: Histology-based classifications and clinical parameters of head and neck squamous cell carcinoma (HNSCC) are limited in their clinical capacity to provide information on prognosis and treatment choice of HNSCC. The primary aim of this study was to analyse Y-box-binding protein-1 (YB-1) protein expression in different grading groups of HNSCC patients, and to correlate these findings with the disease-specific survival (DSS). Methods: We investigated the expression and cellular localisation of the oncogenic transcription/translation factor YB-1 by immunohistochemistry on tissue micro arrays in a total of 365 HNSCC specimens and correlated expression data with clinico-pathological parameters including DSS. Results: Compared with control tissue from healthy individuals, a significantly (P<0.01) increased YB-1 protein expression was observed in high-grade HNSCC patients. By univariate survival data analysis, HNSCC patients with elevated YB-1 protein expression had a significantly (P<0.01) decreased DSS. By multivariate Cox regression analysis, high YB-1 expression and nuclear localisation retained its significance as a statistically independent (P<0.002) prognostic marker for DSS. Within grade 2 group of HNSCC patients, a subgroup defined by high nuclear and cytoplasmic YB-1 levels (co-expression pattern) in the cells of the tumour invasion front had a significantly poorer 5-year DSS rate of only 38% compared with overall 55% for grade 2 patients. Vice versa, the DSS rate was markedly increased to 74% for grade 2 cancer patients with low YB-1 protein expression at the same localisation. Conclusion: Our findings point to the fact that YB-1 expression in combination with histological classification in a double stratification strategy is superior to classical grading in the prediction of tumour progression in HNSCC.