SLC31A1 and metastatic neoplasm: Based on the evidence that the human copper transporter 1 (CTR1) is overexpressed in a variety of cancers, previous works have consistently demonstrated that copper-64 is an authentic tracer for in vivo characterization of copper metabolism in neoplastic tissues of patients affected by metastatic disease spread out of a variety of tumors, including breast and prostate cancers and malignant cutaneous melanoma, by using noninvasive imaging of positron emission tomography (PET) [2–8].