Prognostication of invasive ductal breast cancer by quantification of E-cadherin immunostaining: the methodology and clinical relevance

Aims: We tried to improve the evaluation of E-cadherin immunostaining in paraffin sections, to distinguish the less aggressive variants of ductal infiltrating breast cancer from other variants. Methods and results: The method graded the membrane staining and estimated the fraction of area of cancer tissue stained at the respective staining grade, resulting in an immunohistochemical staining index. At the cut-point 0.35 the index divided all 157 patients (P = 0.0188), and 57 node-positive patients (P = 0.0006) into two groups of different survival. In multivariate analysis (all patients) E-cadherin immunoscore was inferior to mitotic index (SMI) (P = 0.0002), but still significant (P = 0.0031). Among node-positive patients E-cadherin was even more powerful and superior (P = 0.0001) to the still significant SMI (P = 0.0023), and E-cadherin immunostaining and the mitotic activity (SMI) combined did not need the support of other prognosticators in the Cox model. Conclusions: The study suggests that E-cadherin immunostaining can be used efficiently in finding patients with favourable outcome among node-positive patients.