We used the expression level of HIF1A to reflect the level of hypoxia in a tissue sample, with a higher HIF1A expression indicating a higher level of hypoxia.[45]Figure 1 depicts the expression levels of HIF1A in samples in localized, regionally migrated, distantly metastasized, combined cancer samples, and control samples for each of the seven cancer types, respectively. Here, HIF1A is linked to cancer.