Dear Doctor Column, October 3, 2005
Screening for Breast Cancer
Question:
My mother was diagnosed with breast cancer at age 55 and I am worried about developing the disease. I'm 37. Am I too young to have my first mammogram? I've heard there is a new genetic test for breast cancer. Is it something I should consider?
Answer:
More women in the United States are diagnosed with breast cancer than any other type of malignancy except skin cancer — about 210,000 cases annually. Although death rates from breast cancer have declined in recent years, primarily because increased screening has led to detection of the disease at earlier, more treatable stages, only lung cancer causes more cancer deaths in American women. But 5-year survival rates are high — about 97% in women whose cancer has not spread outside of the breast.
Age is the most important risk factor for breast cancer. The disease is relatively uncommon in young women, and most should wait to have their first mammogram until they turn 40. Younger women often have denser breasts that can make mammograms difficult to read, and false positive results are more common. Most women whose mammogram shows an abnormality do not have cancer, but all such findings are followed up with additional testing that can cause anxiety and increase health care costs.
The American Cancer Society (ACS) recommends:
- Women aged 40 and older have a screening mammogram every year. Recent scientific evidence confirms mammograms offer substantial benefits for women in their 40s and older.
- Women in their 20s and 30s have a clinical breast exam (an exam performed by a physician or other health care professional) as part of their regular health care, preferably at least once every 3 years. After 40, women should have a clinical breast exam once a year.
- Starting in their 20s, breast self-examination is an option for all women. Checking your breasts monthly for any changes can help make you aware of what is normal for you. Women who want to do regular breast self-exams should ask their physician to demonstrate proper technique and call their doctor about any changes immediately. It's important to know breast self-exams cannot detect many cancers, especially those at early stages that are too small to feel, and should not take the place of clinical exams or mammography.
Because your mother had breast cancer, you are at increased risk for the disease. Women with risk factors for breast cancer should talk with their doctor about the pros and cons of mammograms and other screening methods, such as ultrasound or magnetic resonance imaging. Your doctor can evaluate all the factors that can increase risk and help you decide if early or more frequent mammograms are right for you.
Besides having a first-degree relative (a mother, sister, or child) with breast cancer, ACS notes other risk factors are:
- Older age: About 77% of women with breast cancer are older than 50 when diagnosed.
- Family history: Having one first-degree relative with the disease approximately doubles a woman's risk of breast cancer; having two close family members with the disease increases risk 5-fold. Having relatives who developed breast cancer before 50, or who have had both breast and ovarian cancer, also increase risk.
- Early age (younger than 12) at first menstruation.
- First child at age 30 or older or never having had children.
- Personal history of breast cancer.
- Previous radiation treatment to the breast or chest.
- Long-term use (more than 3 years) of certain hormones, such as estrogen or progesterone.
- Drinking alcohol.
- Obesity and high-fat diets.
The genetic test you mention is to detect another risk factor for breast cancer — mutations on the breast cancer susceptibility genes 1 and 2 (BRCA1 and BRCA2). Women with BRCA1 or 2 mutations are at greater risk for breast and ovarian cancer, especially when they have relatives with these diseases.
But not all women with alterations in BRCA genes develop cancer, and not all breast and ovarian cancers are caused by the mutations. BRCA mutations are more common in some ethnic groups, such as Ashkenazi (Eastern European) Jews, and among certain families in the Netherlands, Iceland, and Sweden.
Genetic testing for BRCA mutations can help identify women who should consider aggressive screening or other procedures and therapies to reduce cancer risk, such as medication or surgical removal of the breasts or ovaries.
The U.S. Preventive Services Task Force (USPSTF), a panel of independent, private-sector experts that reviews scientific evidence and makes recommendations about preventive health care, recently issued guidelines for BRCA mutation testing, the first time the task force has addressed genetic counseling and testing for any disease.
The task force recommended against routine genetic evaluation if a woman's family history does not confer an increased risk of BRCA mutations. USPSTF says the only women who should be referred for genetic counseling to discuss the benefits and drawbacks of BRCA testing are:
- Women of Ashkenazi Jewish descent with any first- or second-degree relative (a grandparent, grandchild, aunt, uncle, niece, nephew, or half-sibling) with breast or ovarian cancer.
- Women not of Ashkenazi Jewish descent who have: two first-degree relatives with breast cancer, one of whom was diagnosed before age 50; a first degree relative with bilateral breast cancer (cancer in both breasts); a combination of 3 or more first- or second-degree relatives with breast cancer diagnosed at any age; combinations of first- and second-degree relatives with both breast and ovarian cancer; or a history of breast cancer in a male relative (men can develop breast cancer, but it is about 100 times more common among women).
The task force found these women might reap substantial benefits from discussing testing and preventive treatment. However, genetic testing is an emerging technology with complex considerations; the results can affect not only the person tested, but their family members as well. The task force recommended against general testing for BRCA alterations because only about 2% of all women have a family history that puts them at risk for the mutations, and because genetic testing involves risks. Women who test positive may choose to have major surgery or take medications with harmful side affects to prevent the disease. Positive results could also lead to discrimination by employers or insurance companies.
Genetic counseling can help women at risk for BRCA alterations make informed decisions about testing. For more information on genetic testing for BRCA mutations, go to the National Cancer Institute's site. To learn more about breast cancer screening, prevention, and treatment visit the ACS Web site.