MammaPrint Pre-screen Algorithm (MPA) reduces chemotherapy in patients with early-stage breast cancer

Abstract

Breast cancer is the most common cause of cancer mortality in women worldwide and places an increasing burden on health services in both the developing and developed world.[1] Although mortality has decreased over the past two decades, incidence rates continue to increase, particularly in developing countries where the majority of cases are diagnosed at an advanced stage. Breast cancer survival rates also vary greatly between high- and low-income countries, with low survival rates explained mainly by late detection in resource-restricted countries. Breast cancer is a heterogeneous disease characterised by genetically distinct subtypes that differ in their response to treatment.[2] In approximately 20% of breast tumours, over-expression of the human epidermal growth factor receptor 2 (HER2) gene is associated with a poor prognosis and resistance to tamoxifen and methotrexatecontaining chemotherapy regimens, while targeted immunotherapy with Herceptin (trastuzumab) reduces the recurrence rate in these patients by about 50%. Patients with hormone-dependent breast cancer usually respond to a 5-year course of selective oestrogen receptor (ER) modulators, ovarian suppression or aromatase inhibitors. Chemotherapy is generally the only treatment option available for patients with the most aggressive subtype, known as basal-like or triple-negative breast cancer. The benefits of chemotherapy for triple-negative and HER2-positive tumours are well documented. Conversely, only a small minority of patients with ER-positive, progesterone receptor (PR) positive and HER2-negative tumours will benefit from chemotherapy, while all patients with such tumours offered chemotherapy are exposed to its side-effects