Ancillary Techniques.

The presence and quantification of ER and PR in breast carcinoma cells can be evaluated using immunocytochemistry (ICC). Immunostaining can be performed on alcohol-fixed direct smears, like those used for Pap stains, as well as on liquid-based cytology (LBC) preparations and cell block sections. Many laboratories with a long experience in cytology make large use of direct smears for immunocytochemistry, since it is possible to evaluate the adequacy of the sample, and specifically cancer cells can be found in the smear through morphological examination of the Pap-stained slide, which is then destained and used for ICC. However, direct smears may be problematic due to the presence of background material containing significant levels of cellular debris, especially in highly necrotic cancers, which may hinder a proper evaluation. Moreover, even more important, standardization of the ICC results is particularly difficult on direct smears. This is due to the differences in the protocols used for conventional cytology and the consequent differences in the quality of the cellular material. LBC partly solves this problem thanks to its peculiar processing, and it can be very useful for ICC as well as molecular biology analyses [Rossi et al., 2010]. In contrast to direct smears, LBC enables to obtain many slides of comparable Since Elwood V. Jensen’s discovery in 1958 that estrogen receptors play a key role in the growth and survival of most breast cancers and the evidence that hormonal therapies could dramatically alter the history of patients, the diagnosis of cancer has been more and more associated with a series of additional information on prognostic and predictive factors. After that, between the 1990s and early 2000, a second sensational discovery brought another great change in the treatment and prognosis of breast cancer patients, since those with amplification of the human epithelial growth factor receptor 2 (HER2) gene, once burdened with a poor prognosis, could benefit from a targeted therapy, which sensibly improved their survival. Currently, the accurate assessment of the estrogen receptor (ER), progesterone receptor (PR), and HER2 status is essential and mandatory in all breast carcinomas [Allred, 2010]. If until 10 years ago molecular characterization could be performed directly on the surgical specimen, at present a change in the direction of patient management towards neoadjuvant therapies imposes more and more frequently a detailed characterization before surgical treatment, which is based on core biopsy or FNAC material [Hennigs et al., 2016]. The cytopathological methods available for this analysis are mainly immunocytochemistry (ICC) and in situ hybridization (ISH), which are briefly described in this chapter.