Methods

Immunohistochemical Analyses

The molecular characteristics of breast cancer samples are analysed on serial thin sections (6 µm) by immunohistochemistry. A set of eight biomarkers (ER, PR, HER2, EGFR, CK5, p53, p63, and Ki67) is assessed using validated protocols.

During the course of the project, training is provided to centres for immunohistochemical (IHC) analyses. The FHCRC centrally purchased antibody batches, which were aliquoted and distributed to centres (including nonspecific antibodies to be used as negative controls). Successive sections of cases are analysed both in the central pathology laboratory at FHCRC (providing the "gold standard″) and in laboratories at each centre. Under the leadership of Dr Porter, pathological diagnoses and IHC scoring results are reviewed at various time points during the project. Consensus meeting are held using telepathology and image sharing, as well as physical meetings in which stained specimens are reviewed and discussed by all pathologists. Overall, the aim of this procedure is to endow each centre with the capacity to run diagnostic and IHC analyses, while ensuring a high degree of consistency and comparability across centres. This is also critical for prognosis and avoiding delays that may have an adverse impact on therapeutic decisions.