Macroscopic handling and reporting of breast cancer specimens pre- and post-neoadjuvant chemotherapy treatment: review of pathological issues and suggested approaches

Neoadjuvant chemotherapy (NACT) is used increasingly in the treatment of invasive breast cancer and presents challenges for the pathologist in the handling and interpretation of tissues. Potential issues include pathological identification and localization of the residual tumour site; how best to assess pathological response (given the diversity of scoring systems described); the timing and assessment of axillary node biopsy; and the value of retesting any residual tumour for dissonance between core biopsy and post-treatment residual cancer cells for biomarker expression such as oestrogen and progesterone receptors and human epidermal growth factor receptor 2 (HER2). The role of the pathologist is critical in modern NACT approaches to breast cancer and is likely to remain challenging as novel agents and newer biomarkers become available. In this manuscript we review these issues and describe some practical approaches to handling and reporting these samples in the routine histopathology laboratory.