HIF1A and breast cancer: In one previous article based on 100 breast tissue samples, of which 40 represented invasive cancer, HIF-1α-positivity was on the contrary reported to be associated with a high ERα-expression [27], whereas the same group detected a weak correlation between HIF-1α and loss of ERα-expression in a subsequent breast cancer material encompassing 150 patients with stage I-II tumors [13].