The pathway enrichment analysis by GSEA identified the NRF2 pathway as the highest ranked gene signature in the poor responders, and several NRF2-regulated cytoprotective genes were upregulated in ESCC patients with poor responses to CCRT (Fig. 1A; Additional file 1: Fig. S1A–C). This evidence concerns the gene NFE2L2 and esophageal squamous cell carcinoma.