Calculation of the Hypoxia Score

Hypoxia score was calculated based on the 26-gene hypoxia signature (Eustace et al., 2013) and a gene set variation analysis (GSVA) (Eustace et al., 2013; Hänzelmann et al., 2013). GSVA is a GSE method which estimates variation of pathway activity over a sample population in an unsupervised manner (Hänzelmann et al., 2013). Hence, we used the 26-gene hypoxia signature and evaluated the GSVA score of each sample using the GSVA algorithm. The GSVA score was recognized as the hypoxia score, which represented the hypoxia status of each sample. The cut-off value was identified according to the method of best separation in R package survminer, and patients were divided into high- and low-hypoxia score groups. Such grouping aims to minimize the P value of the survival curve. Additionally, T-test was used to judge the differences of clinical indexes between groups.