Prognostic impact of H3K27me3 expression on locoregional progression after chemoradiotherapy in esophageal squamous cell carcinoma

The method of immunohistochemistry (IHC) was utilized to examine the protein expression of H3K27me3 in 98 pretreatment biopsy specimens of ESCC and in 30 samples of normal esophageal mucosa. The clinical/prognostic significance of H3K27me3 expression was statistically analyzed.The expression frequency and expression levels of H3K27me3 were significantly higher in ESCCs than in normal tissues. There was a positive correlation between H3K27me3 expression and WHO grade (P = 0.016), tumor size (P = 0.019), T status (P = 0.024), locoregional progression (P = 0.009) and EZH2 expression (P = 0.036). High H3K27me3 expression was associated with poor locoregional progression-free survival (LPFS) (P = 0.010) in ESCC. Further analysis demonstrated that H3K27me3 could stratify patient outcome in T2-3 (P = 0.048), N0 (P = 0.005) and M0 (P = 0.018) stages as well as in CRT effective group (P = 0.022).Our data suggests that H3K27me3 expression examined by IHC might be useful for stratifying LPFS for different subsets of ESCC patients treated with definitive CRT.Esophageal squamous cell carcinoma (ESCC) is an aggressive human cancer with poor prognosis worldwide [1]. Most patients present with locally advanced disease, and definitive chemoradiotherapy (CRT) is an important component of the therapeutic strategy for ESCC [2]. Despite the great advances achieved in radiotherapy technology recently, its overall 5-year survival rate remains less than 30%, and the high probability of recurrence is still the main cause of poor quality of life and death [3]. At present, only the stage based on Tumor Node Metastases (TNM) classification and primary complete response to CRT are widely accepted as prognostic factors [4]. However, there are substantial differences in survival within patients with the same clinical stage and/or CRT response, probably attributable to the differences in biologic behavior of the tumors. Improved prognostic markers that can further stratify patient outcome are ther