Intratumoral hypoxia is a stimulus for the induction of HIF-1α and HIF-2α protein expression, and increased expression of one or both of these proteins, as detected by immunohistochemical analysis of the diagnostic tumor biopsy, is associated with increased patient mortality in a wide range of solid cancers and leukemias (n = 101 studies; Supplemental Table 1; supplemental material available online with this article; https://doi.org/10.1172/JCI159839DS1). Here, EPAS1 is linked to neoplasm.