Informative Tools to Optimize Neoadjuvant Therapy in ER Positive, HER2 Negative Breast Cancers

Based on what is known about the treatment of breast cancer, there are occasional advantages to giving treatment before surgery. Some of these advantages can include shrinking a large breast cancer to facilitate surgery, shrinking a breast cancer to allow breast conservation (avoid a mastectomy), and evaluating how effective a treatment is in real-time, based on its effect on the breast cancer. When recommending treatment with hormone therapy and/or chemotherapy, doctors take into consideration all the characteristics of a breast cancer. Over recent years, is has been recognized that additional tests can help predict the behavior of a cancer and predict the possible benefit of hormone therapy and/or chemotherapy. Because there is no way to identify exactly who benefits from chemotherapy, many patients receive chemotherapy when they might not need it. This study involves the use of 2 separate tests. The first is called Ki-67 and is done using a piece of tumour that is taken during a needle biopsy. The second, called the Oncotype DX, is made by Genomic Health, Inc, located in Redwood, CA, USA. This test also uses a piece of tumour that was retrieved during a needle biopsy. The pieces will be tested in a specialized laboratory that can measure the levels of a specific set of genes in the tumour. The laboratory that performs this test (Redwood, CA, USA) has been certified by federal and state agencies in the United States to perform the test (called Oncotype DX). The results of the test are turned into a score (called Recurrence Score) that has been used for patients receiving treatment after surgery, but has not yet been used when treatment is given before surgery. The standard practice for this type of cancer is for the patient and their doctor to decide whether they should receive chemotherapy in addition to hormone therapy or to take hormone therapy alone, prior to surgery. The Ki-67 is inconsistently used in British Columbia prior to surgery, but may be used routinely in other centers. Usually, the Oncotype DX test is not available to aid in this decision outside of a research study.