About one in eight women in the United States will develop breast cancer, according to commonly used statistics.
But other reports indicate that breast cancer rates are on the decline, likely because of improved recognition, prevention, and treatment. One advancement is the ability to identify different breast cancer types based on specific molecules found in tumors. The distinction greatly aids in breast cancer treatment selection and helps doctors predict how aggressive cancers will advance.
A crucial step in the process of beast cancer evaluation is testing tumor tissue removed during a biopsy or surgery to determine if it has estrogen and progesterone receptors – molecules that the hormones bind to.
Cancerous cells may have none, one, or both receptors. Breast cancers that have estrogen receptors are called ER-positive (or ER+). Those with progesterone receptors are referred to as PR-positive (or PR+).
In addition to hormone receptors, some breast cancers have high levels of a growth-promoting protein called HER2/neu. If a tumor has this property, it is called HER2-positive. HER2 positive cancers are more aggressive than HER2 negative cancer.
Knowing breast cancer type, leads doctors to determining best treatments.
For example; in ER positive/HER2 negative breast cancer, tumors that are ER positive are much more likely to respond to treatments that block estrogen. Treatment possibilities include selective estrogen-receptor response modulators (SERMs), aromatase inhibitors, estrogen-receptor downregulators (ERDs) and luteinizing hormone-releasing hormone agents (LHRHs).
HER2 negative cancers will not respond to treatment with drugs that target HER2, such as trastuzumab (Herceptin) and lapatinib (Tykerb).
The most common treatment for ER positive and HER2 negative breast cancer is hormone blocking therapy. Although chemotherapy can also be used, no specific type is recommended by the American Society for Clinical Oncology (ASCO). Available drugs can include taxanes, anthracyclines, platinum-based drugs, capecitabine (Xeloda), eribulin (Halaven), gemcitabine (Gemzar), ixabepilone (Ixempra), and vinorelbine (Navelbine).
The prognosis for patients with ER+ and HER2- breast cancer depends on how advanced the cancer was when it was detected. Prognosis is also influenced by the size of the tumor and if the cancer has spread to other organs.
Most women with very early stage breast cancers will live a normal lifespan. Five-year survival rates are based on the stage (0-4) of breast cancer according to the American Cancer Society, with stage 4 at 22% and stage 0 at 100%. Stage 4 is metastatic breast cancer, which means that cancerous cells have spread to other regions of the body.
Overall, estrogen receptor-positive breast cancer is treatable, especially when diagnosed early.