Since patients in this study had very widespread disease with more than five metastatic lesions, a perspective for future studies could be to explore the impact of [18F]FDG-PET/CT as follow-up after high-risk early-stage breast cancer, i.e., patients treated for locally advanced breast cancer, extensive lymph node involvement in the axilla, triple-negative, and HER2 positive breast cancer. Here, ERBB2 is linked to breast carcinoma.