Breast Cancer

Breast cancer is the second most commonly diagnosed cancer and the second leading cause of cancer deaths among women in the United States.1 In 2009, more than 192,000 American women will be diagnosed and more than 40,000 Americans will die from the disease.1 There are approximately 2.5 million breast cancer survivors in the United States.9

Breast cancer is the uncontrolled growth of cancerous cells that originate in breast tissue. In advanced breast cancer, the cancer has spread (metastasized) to other parts of the body, most commonly the lungs, bones, liver and brain.2 While the causes are unknown, there are many forms of breast cancer based in part on genetic characteristics, such as human epidermal growth factor receptor-2 (HER2)-positive and HER2-negative. Each form of breast cancer has a different prognosis. The American Society of Clinical Oncology recommends that all women diagnosed with breast cancer have tumor marker tests, which can help predict how a tumor may behave and help determine the best treatment options.3


  • One in four women has HER2-positive breast cancer, a more aggressive type associated with a poorer prognosis.4
  • Overabundance of the HER2 protein classifies the breast cancer as HER2-positive and causes breast cancer cells to multiply, spread more rapidly and survive longer than other breast cancers.5
  • Women with HER2-positive disease are often treated with medicines targeting the HER2 protein; the first targeted medicine for HER2-positive breast cancer was approved in 1998, significantly changing the approach to treating these individuals.


  • Three in four women have HER2-negative breast cancer, which does not spread as quickly as HER2-positive disease, but remains an aggressive cancer.
    • Some women have a more difficult-to-treat form of HER2-negative breast cancer known as "triple-negative," which means they test negative for three main receptors (HER2, estrogen receptor [ER] and progesterone receptor [PR]).6
  • Women with HER2-negative breast cancer may be eligible for a targeted medicine that received accelerated approval in February 2008 from the U.S. Food and Drug Administration.

Risk Factors And Symptoms

  • Age - the diagnosis of breast cancer, as well as death from the disease, increases with age; the vast majority of new cases (95 percent) and deaths (97 percent) occur in women over the age of 40.1
  • Risk factors - inheritance of specific genes, history of breast abnormalities, age of first menstrual period, family history of breast cancer, obesity, physical inactivity and race.1
  • Symptoms - the earliest sign of breast cancer is usually detected by a mammogram before it can be felt or by the presence of a painless lump detected during a self-exam;1 less common symptoms include changes to the breast or nipple such as thickening, swelling, tenderness, skin irritation, redness and scaliness.1

Prognosis And Survival

  • The number of women dying from breast cancer has declined since 1990, primarily due to improvements in treatment and early detection; many women with early-stage disease can be cured if it is found early enough.1
  • Only 27 percent of women whose breast cancer has spread to other parts of the body will live for five years.1
  • African-American women diagnosed with breast cancer are less likely than Caucasian women to survive five years, primarily due to later-stage detection.11
    Stage Description 5-Year Survival Rate7
    I Tumor is only in the breast and < 2 centimeters (cm) 100%
    II Tumor has spread to lymph nodes in the breast and < 5 cm 86%
    III Tumor has spread to 4-9 lymph nodes or to the chest wall or skin 57%
    IV Tumor has spread to distant organs 20%
  • Women with HER2-positive breast cancer are at a much higher risk for early recurrence and death as a result of their disease, compared to women with HER2-negative breast cancer.
    • One study found that women with small tumors were nearly six times more likely to have a recurrence within two years of diagnosis and 11 times more likely to die from their breast cancer.8
    • Women with large tumors were three times more likely to have a recurrence within two years of diagnosis and nearly four times more likely to die from their breast cancer.8
  • Only half of women with HER2-negative advanced breast cancer will live for three years.12

Early-Stage Treatment

  • Early-stage breast cancer can be treated locally by surgery or radiation to remove, destroy or control the cancer cells.1
  • Women with early-stage HER2-postive breast cancer may be eligible to receive medicines that target the HER2 protein after initial treatment (surgery or radiation) to help reduce the risk of the cancer returning or spreading (adjuvant treatment).1
  • Other individual factors, including size and location of the cancer cells, can influence whether chemotherapy, hormone treatment or targeted medicines can be used.1

Advanced-Stage Treatment

  • When cancer has spread, the choice of treatment generally depends on the type of cancer, size and how far it has advanced, the person's age and general health, and previous treatment.2
  • Chemotherapy, radiation therapy, targeted medicines, hormone treatments, surgery or a combination are typically used for advanced cancer.2
  • Cure is an unlikely outcome for advanced breast cancer; goals of treatment include symptom relief, improving quality of life, keeping the disease from worsening and increasing survival.10