As our knowledge of tumor biology improves, our researchers are seeking to identify more-precise molecular markers that can help predict how a patient will respond to a specific treatment. We’ve been evaluating hormone receptors, cancer-related genes (called oncogenes), and certain enzymes produced by cancer cells that help the cells to spread. We’re particularly focused on the role of genetic mutations (such as those in the BRCA1 and BRCA2 genes) in the development and progression of breast cancer and how it responds to treatment.
Our goal is to integrate these laboratory research findings into the care we offer you, so that we can customize your treatment based on the specific molecular signals that are driving the growth of your cancer.
We’ll also want to learn about other elements that can affect your treatment plan, including:
Breast cancer cells that have receptors for the hormone estrogen are called estrogen receptor positive, and those with receptors for the hormone progesterone are called progesterone receptor positive. If these receptors are not present, the cell is said to be hormone receptor negative. Tumors that are hormone receptor positive are more likely to respond to therapy with antiestrogen medications, which take advantage of the cancer cell’s dependence on hormones for growth. The drug tamoxifen, for example, acts by blocking the estrogen receptors of a breast cancer. Another class of drugs called aromatase inhibitors, used in postmenopausal women, interferes with the production of estrogen.
Oncotype DX® is a test that is used to analyze 21 genes in patients with a breast tumor that is estrogen receptor positive and has not spread into the axillary (underarm) lymph nodes. Information is translated into what is called a recurrence score, which enables doctors to predict which women will benefit most from chemotherapy and which women will not.
HER2/neu is a gene that, when activated, helps tumors grow by producing a specific growth-stimulating receptor. Tumors that have higher than normal amounts of this protein (HER2 positive) may respond to the drug trastuzumab (Herceptin®), which blocks the growth of tumors activated by the gene, or a similar drug called lapatinib (Tykerb®).
About 10 to 15 percent of breast cancers don’t contain receptors for estrogen, progesterone, or HER2/neu. They are called triple-negative breast cancers. These are particularly difficult to treat successfully because they don’t respond to such drugs as tamoxifen, anastrozole, trastuzumab, and lapatinib. Triple-negative breast cancers also tend to be more aggressive, occur earlier in life, and pose a greater risk of returning than other types of breast cancer. Women with triple-negative breast cancer may be more likely to carry a BRCA mutation, especially if they are diagnosed at a young age. Our researchers and others around the world are studying the biology of triple-negative breast cancer to learn more about the disease and hopefully identify new therapeutic targets.