Monthly Highlight: Guiding Treatment of Advanced Breast Cancer Using Subtypes

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For patients with breast cancer, knowing whether the diagnosis is early stage or advanced is needed to help treat the disease. Vice-President and Chief Medical Officer for Georgia Cancer Specialists, Cheryl Jones, MD, has experience in treating patients with advanced breast cancer, an incurable but treatable disease, which comprises metastatic (stage IV) and locally advanced (stage III) breast cancer. Metastatic breast cancer occurs when the cancer spreads to other parts of the body and is treated differently than earlier stages of the disease.

Dr. Jones explains the importance of understanding tumor subtypes to help patients become more involved in treatment discussions. Here she addresses questions about the different subtypes, which include human epidermal growth factor receptor-2 positive (HER2+) and hormone receptor-positive (HR+).

Q: How do HR and HER2 status help determine a treatment plan?

Dr. Jones: Each tumor’s genetic makeup helps oncologists identify the best approach to the treatment of advanced breast cancer. HR+ tumors, which occur in approximately 70 percent of cases, are fueled by hormones like estrogen and progesterone. Therefore, postmenopausal patients may benefit from hormonal therapy, such as an aromatase inhibitor, which blocks the production of estrogen from helping the cancer grow. If the breast cancer is HR-, accounting for about 15-20 percent of cases in the US, then we treat with drugs other than hormonal therapy, such as chemotherapy. If the tumor overexpresses the HER2 gene it is known as HER2+ and requires aggressive treatment such as with drugs that target the HER2 protein. This occurs in about one in five breast cancers.

Q: What are the biggest considerations when treating advanced breast cancer subtypes?

Dr. Jones: For advanced HR+/HER2- breast cancer, we consider how this type can outsmart hormonal therapy over time and become resistant, resulting in tumor progression. Treatments exist that may extend the benefits of hormonal therapy. For example, Afinitor (everolimus) is a prescription medicine used to treat advanced HR+/HER2- breast cancer, along with the medicine exemestane (an aromatase inhibitor), in postmenopausal women who have already received certain other medicines for their cancer. Afinitor can cause serious side effects, including lung or breathing problems, infections and kidney failure which can lead to death. Even though HER2+ tumors tend to be more aggressive, HER2 targeted treatments also exist. Tumors that are both HER2- and HR-, known as triple negative breast cancer, cannot be treated with HER2 targeted or hormonal therapies, so we will commonly use a combination of surgery, radiation and chemotherapy.

Visit Afinitor to learn more about advanced HR+/HER2- breast cancer.

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