ERBB2 and breast cancer: Conversely, when further stratifying BC molecular subtypes in 5 classes (Luminal A, Luminal B HER2-negative, Luminal B HER2-positive, HER2-enriched and triple-negative), Elboga et al. showed a trend for increasing SUVmax values from Luminal A (lower values) to Luminal B HER2-positive type and HER2-enriched tumors (higher values); moreover, HER2 expression seems to confer the highest 68Ga-FAPI activity among the Luminal group, with significantly higher uptake in Luminal B HER2-positive vs. Luminal A or Luminal B HER2-negative groups [32].