Breast cancer continues to be one of the most common malignancies and is a serious problem particularly in women, although men may also be affected. Such lesions are commonly accompanied by hypoxia, and therefore hypoxia-dependent mechanisms, such as overexpression of hypoxia-inducible factor (HIF), the mechanisms are studied as part of the search for a novel method of cancer treatment. Blocking the activity of HIF and HIF-dependent molecular changes raises hopes for identification of a molecular target to inhibit the tumor growth or even to completely prevent its progression. However, this is difficult due to the crucial role HIF plays in numerous processes occurring not only in cancer cells but mostly in healthy systemic cells in physiological conditions.