The suitability of FDG-PET/CT has already been proven in breast cancer (12-14), but its efficacy depends on several tumor-properties, for instance histological tumor type (invasive ductal carcinomas are better candidates for PET/CT examinations than invasive lobular cancers) or proliferation rate (high Ki-67 LI is favorable in this respect) (47-49). The gene discussed is MKI67; the disease is invasive ductal breast carcinoma.