PGR and breast neoplasm: Consistent with these observations, among the most aggressive human breast tumors, triple‐negative breast cancers (TNBCs), a clinically heterogeneous category of breast tumors that lack expression of estrogen receptor, progesterone receptor, and human epidermal growth factor receptor 2 (HER2), show profound metabolic alterations with impaired mitochondrial oxidative metabolism (Elias, 2010; Owens et al, 2011).