Pathological definitions of invasion, metastatic potential and responsiveness to targeted therapies

The tailored treatment of patients with primary breast carcinoma relies mainly on the assessment of invasion, metastatic potential and responsiveness to targeted therapies. Accordingly, the role of the pathologist is to ensure the most accurate evaluation of the prognostic and predictive parameters, which will have a major impact in the planning of the adjuvant interventions. Every effort has to be made to improve the accuracy and the inter-laboratory reproducibility of the histopathological and biological characterization of breast carcinomas, taking advantage of the newly developed molecular assays. This review article will focus mainly on some controversial issues, like intracystic papillary carcinomas, whose invasive or non-invasive nature is still debated; the suitability of sophisticated molecular assays to assess the metastatic potential of primary breast carcinomas better than what is currently done; and the need for modifying the scoring criteria of the assays to assess tumor responsiveness to anti-HER2 treatments.