Breast cancer-BC is a type of cancer that develops in the breast tissue. It is the most common cancer among women worldwide. So the current study aimed to evaluate the activity of serum proline dehydrogenase-PRODH and some biochemical parameters in sera of women with breast cancer as an indication for treatment response. Ninety serum samples were collected from women with and without breast cancer-BC, 30 samples were collected from women with BC(newly diagnosed cases) as the first group-G1 and 30 samples were collected from patients with BC after undergoing chemotherapy as second group-G2. While a 3rd group is a control group C which was collected from 30 healthy women.
           The study includes the determination of PRODH, Metaloendopeptidase-MME, Catalase-CAT and Glutathione-S-transferase –GST activity and also the determination of the level of cancer antigen-15-3-CA15-3 and peroxynitrite –PNT in sera of groups under investigation.
           The results of the study indicate:   In G1 the level of CA15-3 and CAT significantly elevated(P≤0.05), with no significant difference in PRODH, MME, and GST  and a significant reduction in the level of PNT as compared with G2 and C, While in G2 the level of PRODH, MME, CAT, and PNT significant difference as a response for treatment, with no significant difference in CA15-3 and GST  as compared with G1and C.
            We can conclude that the enzymes (PRODH, MME, and GST ) may serve as a potential therapeutic target for breast cancer.