ESR1 and complete blood cell count: The study by Piscuoglio et al. [59], encompassing 59 MBC cases, of which 97% were ER-positive/HER2-negative tumors (71% luminal B-like), sequenced 241 genes most prevalent in FBC, demonstrating that PIK3CA, GATA3, TP53, and MAP3K1 were significantly mutated.