However, we have to emphasize that the number of primary tumors that we tested was very low, since these are not randomly selected samples, but highly selected paired samples, where ctDNA and CTCs were also available, and our main aim was not to show the incidence of PIK3CA mutations in primary breast tumors but to compare the PIK3CA mutational status in primary tumors, CTCs and ctDNA. This evidence concerns the gene PIK3CA and breast neoplasm.