Breast cancer is the most common cancer among women, but there is some good news about the breast cancer epidemic.
After increasing for more than 20 years, new cases have been declining by about 2% each year since 1998 in women over 50. Researchers believe this is partly due to the declining use of hormone replacement therapy (HRT) after menopause, which followed publication of a study that linked HRT to increased breast cancer risk. Deaths from breast cancer also have declined since 1990, thanks to earlier detection and improving therapies.
For many women, breast cancer can now be managed as a chronic disease. When found early before a tumor has spread, 5-year survival is 99%. Overall, 10-year survival rates for all stages of disease have climbed to 82%. Early detection is vital: survival rates are still poor for women diagnosed with late-stage metastatic cancer that has spread to other parts of the body.
Women have a higher risk for developing the disease if breast cancer runs in their families and if they have certain inherited gene mutations (BRCA1 and BRCA2). They have a lower risk if they have had children and have breast fed. Obesity increases risk for many cancers, including breast cancer; the rise in obesity could threaten the downward cancer trends seen in recent years.
Genetics research is giving scientists and physicians deeper understanding of different types of breast cancer. Three general types have been identified. In one type, tumor growth is driven by signals through estrogen receptors on cell surfaces; an estimated 60% of women have this type. About 25% of women have the second type, in which tumor growth is driven by another type of receptor, called “HER2.” In the third type, neither estrogen nor HER2 receptors play a role.
The ability to identify cancer subtypes is advancing therapy, allowing physicians to tailor treatment for the individual patient and improve its effectiveness. For example, women who are HER2 positive can be treated with Herceptin, a hormonal therapy that targets HER2.
Treatment usually combines surgery to remove tumors and affected lymph nodes, followed by some combination of radiation, chemotherapy and hormonal therapy. The treatment approach depends on the stage (tumor size) and spread of the disease. Genetic features and biological markers (biomarkers) of an individual’s tumor are also used to guide treatment plans.
American Cancer Society, Cancer Facts and Figures 2012