Breast cytology, in particularly fine needle aspiration biopsy (FNAB), has been used for many years as a
diagnostic tool for managing patients with breast lesions. In experienced hands, FNAB is highly sensitive and specific.
Other benefits include its low cost, minimal invasiveness, and ability to provide same-day diagnosis. Despite all these
benefits, FNAB has gradually been replaced by core needle biopsy (CNB) because of its high error rates when there is a
lack of experienced cytopathologists, its inability to distinguish between invasive and in situ carcinoma, and most
importantly, its inability to provide adequate and suitable materials for quantitative evaluation of HER2 and other
prognostic markers. Other uses of breast cytology include touch preparation cytology for intraoperative evaluation of
sentinel lymph nodes and surgical margins of lumpectomy specimens and for providing same-day diagnosis of CNB. In
addition, breast cytology, such as ductal lavage and nipple fluid cytology, has also found applications in risk assessment
for women at high risk for developing breast cancer. With the increased utilization of molecular technologies, genomic
and proteomic studies have been successfully applied to breast cytologic preparations. It would not be far fetched to
predict that in the very near future, the clinical application of molecular analyses will be routine ancillary testing in breast
cytology, thus allowing early cancer detection, and improved tumor characterization as well as prediction of patients'
outcomes and therapeutic responses.