In the present study, TCA cycle enzymes such as isocitrate dehydrogenase (IDH), succinate dehydrogenase (SDH), and malate dehydrogenase (MDH) were found to be decreased in the DMBA-induced breast cancer animals (585 ± 15.5 μmoles of α- ketoglutarate/min/mg protein; 35.4 ± 0.303 μmoles of succinate oxidized/min/mg protein; 213 ± 3.52 μmoles of NADH oxidized/min/mg protein). This evidence concerns the gene IDH3A and breast cancer.