ESR1 and neoplasm: As shown in Table 1 HER2 ECD positivity was significantly associated with being older (p = 0.002), having lymph node involvement (p = 0.010), having an advanced stage (p < 0.0001), having a high histological grade (p = 0.029), the presence of non-diploid tumor DNA (p = 0.033), having a negative ER (p = 0.0002), having a negative PR (p = 0.015) and HER2/neu overexpression (p = 0.003).