21st century breast pathology 101

Abstract

Scientific and medical research especially over the last 20 years has had a huge impact on breast cancer patients’ lives. The modern multidisciplinary approach to screening, diagnosis and treatment has come a long way since the early days when the aetiology of many cancers was poorly understood and therapy options were limited. Modern imaging techniques together with specialised operator expertise have ensured that the correct targeted tissue samples are rapidly available for diagnosis and further testing. We now clearly understand that not all breast cancers are the same and the classification and re-classification process of tumours has evolved and improved each year with quite dramatic changes made in the last decade. EndoPredict™® is a very useful modern assay to determine the risk of distant metastases. Following the histologic classification and grading of cancers, the key to determining the correct treatment for a patient is identifying the molecular subtype of a breast cancer. The three major groups based on molecular signatures are hormone receptor positive, HER2 positive and triple negative. Modern therapy involves a combination of hormonal manipulation, targeted drugs, surgery, chemotherapy and/or radiotherapy. As with antibiotics and bacteria, unfortunately it is also common for breast cancer to become resistant to first line drug therapy (endocrine resistance) and so new treatment options are being continually developed. Laboratory testing on paraffin embedded breast core biopsies has now greatly improved the sensitivity and specificity of HER2 gene amplification status detection by techniques such as FISH, CISH, SISH, DISH and qPCR. Molecular techniques are now available to determine susceptibility genes for familial breast cancer including BRCA1, BRCA2, TP53 and CHEK2.