Scintigraphic Images of Breast Cancer With Tc-99m Cysteine

Cysteine is a nonessential amino acid and has been shown to increase levels of the antioxidant glutathione. When a cancer process begins, the tumor cells show an abnormal increment in their metabolism and mitosis. This requires additional amounts of amino acids to produce the different proteins necessary to maintain cell functions. Because the applications of metabolic imaging are expanding, radiolabeled amino acids may gain increased clinical interest. Several authors have been reporting the use of amino acids and their derivatives for the detection of tumors cells. An example is I-123 methyl tyrosine. On the other hand, the easily performed procedure of labeling cysteine with Tc-99m provides a possibility to use radiolabeled cysteine as a radiopharmaceutical for breast cancer diagnosis. The authors present 2 cases—a 45-year-old woman with an infiltrating ductal carcinoma and axillary nodule. The breast tumor and the axillary nodule were visualized with scintimammography with Tc-99m cysteine. The other case is a 40-year-old woman with infiltrating lobular carcinoma who had scintimammography with Tc-99m cysteine showing focal uptake in the lateral right view.