The overall 5-year survival rate for breast cancer is now 89%—a dramatic improvement over the early 1960s when the rate was 63%. When considered by stage, the 5-year survival rates are 99% for localized disease and 85% for regionally advanced disease that may have spread to neighboring lymph nodes. For patients with stage 4 disease with distant metastases, the 5-year survival rate drops to 26%.
Increased risk for breast cancer is associated with a personal or family history of the disease and inherited genetic mutations in breast cancer susceptibility genes; these include BRCA1 and BRCA2 and other less common inherited gene mutations. An inherited predisposition to develop breast cancer accounts for approximately 5%-10% of all breast cancer cases, but is rare in the general population (less than 1%). Women with BRCA1 and BRCA2 mutations have an estimated 45% to 65% lifetime risk of developing breast cancer. Other known risk factors include obesity, use of MHT (a hormone therapy that combines progestin and estrogen), high breast tissue density, alcohol consumption, and physical inactivity.
When diagnosed early, breast cancer treatment generally involves surgery, which, depending on the stage and molecular characteristics of the cancer, may be followed by chemotherapy, radiation therapy, or targeted therapy (including hormone therapy).
Cancers over-expressing a protein receptor called HER2 (HER2 3+, or FISH-positive) may be treated with targeted immunotherapies such as trastuzumab (Herceptin®) and pertuzumab (Perjeta®) and, in the case of advanced cancer, trastuzumab emtansine (Kadcyla®). Of these, the newest treatment options are pertuzumab and trastuzumab emtansine. Pertuzumab was approved by the FDA in 2012 for first-line treatment of HER2+ metastatic breast cancer in combination with trastuzumab and the chemotherapy docetaxel (Taxotere). Ado-trastuzumab emtansine is a HER2-targeted antibody with chemotherapy (a microtubule inhibitor) attached by a linker, and is designed to deliver chemotherapy directly to the tumor via HER2. Ado-trastuzumab emtansine was approved by the FDA in 2013 for patients with HER2-positive, metastatic breast cancer who have previously received trastuzumab and taxane chemotherapy separately or together.
Setting the stage for combining trastuzumab and pertuzumab, in 2005, Yosef Yarden, Ph.D., a 1987 CRI Postdoctoral Fellow, first demonstrated in the laboratory that combining trastuzumab with an antibody directed against a different part of HER2 is more effective than trastuzumab alone against HER2+ breast cancer .
Although treatment with trastuzumab and other HER2-directed therapies are associated with significant efficacy, only patients with the highest levels of HER2 expression, representing approximately 20% of breast cancer patients, have the potential to respond. Moreover, many patients expressing high levels of HER2 progress or relapse despite receiving the best HER2-directed treatments, and thus require novel treatment approaches. Additionally for patients with ER+ or PR+ breast cancer who are refractory to endocrine therapy, or patients who have triple negative breast cancer, targeted therapeutic options remain quite limited. New therapeutic strategies for breast cancer are needed to improve clinical outcomes for breast cancer patients, particularly those with advanced disease.
Because current treatments are unlikely to cure advanced breast cancer, patients in otherwise good health are encouraged to think about taking part in clinical trials. Go to our Clinical Trial Finder to find clinical trials of immunotherapies for breast cancer that are currently enrolling patients.