In a prospective study of 254 patients, the rates of extra-axillary lymph node metastases on 2-[18F]FDG PET/CT were higher in grade 3 than in low-grade tumours (p = 0.004) and in triple-negative or HER2 + tumours compared to ER + /HER2 − tumours (p = 0.01) [37]. Here, ERBB2 is linked to neoplasm.