Breast cancer is the second most common form of cancer and second leading cause of cancer deaths among American women, causing more than 40,000 deaths annually. In 2008, an estimated 182,000 American women will be diagnosed with breast cancer. Currently, there are approximately 2.5 million breast cancer survivors in the United States.1
What is Breast Cancer? Breast cancer is defined as the uncontrolled growth of malignant (cancerous) cells that starts in breast tissue. Researchers now understand that breast cancer is not one, but many different diseases. Even when tumors are classed together based on their appearance, they can act differently because of different genetic makeup.2 Metastatic breast cancer is cancer that has spread from the breast to other parts of the body. The most common sites of breast cancer metastasis are the lungs, bones, liver, and brain.3
The exact causes of breast cancer are unknown but risk factors include: gender, age, inheritance of specific genes that can cause breast cancer, personal history of breast abnormalities, age at first menstrual period, age at first live birth, breast cancer history of close relatives, obesity, physical inactivity, and race.4
What are the Stages of Breast Cancer? There are four main stages, which reflect the extent or severity of disease, ranging from Stage I (least advanced) through Stage IV (most advanced). The stage takes into account the size of the tumor, whether the cancer has spread to lymph nodes, and whether it has spread to distant organs (metastasis).5
What are the Different Types of Breast Cancer? There are many types, though some are very rare, and sometimes a breast tumor can be a combination of types.2 Among breast cancer patients, the status of hormone receptors (estrogen receptor and progesterone receptor) and human epidermal growth factor receptor-2 (HER2) are important prognostic markers that guide treatment decisions.
- Estrogen Receptor (ER) and Progesterone Receptor (PR) Status: Evaluating the presence of ER and PR can show whether one or both of those hormones is causing the tumor to grow. Treatment decisions are based on their status because breast cancers that are ER-positive, PR-positive, or both tend to shrink, or stop growing, when treated with therapies that block the hormone receptor.6
- HER2 Receptor Status: HER2-positive breast cancer, which occurs in approximately 25 percent of women with breast cancer, is characterized by aggressive growth and a poorer prognosis.7 It is caused by the presence of excessive numbers of a gene called HER2 in tumor cells.8 Patients with HER2-positive disease are often treated with therapies targeted against the HER2 pathway.
HER2-negative breast cancer represents the largest population, accounting for approximately 75 percent of newly diagnosed advanced breast cancers.
How is Breast Cancer Treated? Treatment depends upon many individual factors, including the size and location of the tumor, receptor status and disease stage. Overall, breast cancer treatments are characterized as local or systemic:9
- Local treatments are used to remove, destroy or control the cancer cells in a specific area. Surgery and radiation treatment are local treatments.
- Systemic treatments are used to destroy or control cancer cells all over the body. Chemotherapy, hormone therapy, and targeted biologic therapy are systemic treatments. A patient may have just one form of treatment or a combination, depending on her needs.
When cancer has spread (metastasized), the choice of treatment generally depends on the type of primary cancer, size and location of the metastasis, patient's age and general health, and types of previous treatments. Chemotherapy, radiation therapy, biological therapy, hormone therapy, surgery, cryosurgery (a procedure in which tissue is frozen to destroy abnormal cells), or a combination, are typically used to treat advanced cancer.3 For many cancers, cure is the expected goal of treatment, particularly if diagnosed at an early stage. However, cure is an unlikely outcome for metastatic breast cancer; as a result, other goals are of greater importance, including relief of symptoms, improved quality of life, longer survival, and longer progression-free survival.10
What is the Survival Rate of Breast Cancer? According to the American Cancer Society, the death rate for women with breast cancer has declined since 1990, primarily due to improvements in treatment and early detection. Recent estimates show that the five-year survival rate for women with metastatic breast cancer is 27 percent.1
African-American women diagnosed with breast cancer are less likely than Caucasian women to survive five years primarily due to later-stage detection.1 Additionally, researchers have found that African-American and Hispanic women are more likely to be diagnosed with a difficult-to-treat type of breast cancer known as triple negative, which means they test negative for all three receptors (ER, PR and HER2). These patients previously had limited treatment options because available therapies only targeted tumor cells that tested positive for the three receptors.11
1 American Cancer Society. Breast Cancer Facts and Figures 2008-2009. http://www.cancer.org. Accessed March 20, 2008.
2 American Cancer Society. Cancer Reference Information: What is Breast Cancer? Accessed January 9, 2008.
3 National Cancer Institute. Metastatic Cancer: Questions and Answers. Accessed January 9, 2008.
4 American Cancer Society. Cancer Reference Information: What Causes Breast Cancer? Accessed January 9, 2008.
5 American Cancer Society. Cancer Reference Information: After the Tests: Staging. Accessed January 9, 2008.
6 BreastCancer.org. Hormone Receptors. Accessed January 11, 2008.
7 BreastCancer.org. Will Herceptin Work for You? Accessed January 9, 2008.
8 BreastCancer.org. How Herceptin Works. Accessed January 9, 2008.
9 American Cancer Society. Cancer Reference Information: How is Breast Cancer Treated? Accessed January 9, 2008.
10 Chung, CT, Carlson, RW. Goals and Objectives in the Management of Metastatic Breast Cancer. The Oncologist 2003;8:514-520.
11 Reynolds, S. National Cancer Institute Cancer Bulletin. July 24, 2007. Accessed January 9, 2008.