Breast Cancer Prevention (cont.)
Melissa Conrad Stöppler, MD
Melissa Conrad Stöppler, MD, is a U.S. board-certified Anatomic Pathologist with subspecialty training in the fields of Experimental and Molecular Pathology. Dr. Stöppler's educational background includes a BA with Highest Distinction from the University of Virginia and an MD from the University of North Carolina. She completed residency training in Anatomic Pathology at Georgetown University followed by subspecialty fellowship training in molecular diagnostics and experimental pathology.
William C. Shiel Jr., MD, FACP, FACR
Dr. Shiel received a Bachelor of Science degree with honors from the University of Notre Dame. There he was involved in research in radiation biology and received the Huisking Scholarship. After graduating from St. Louis University School of Medicine, he completed his Internal Medicine residency and Rheumatology fellowship at the University of California, Irvine. He is board-certified in Internal Medicine and Rheumatology.
In this Article
- Introduction to breast cancer prevention
- What are the biological causes of breast cancer?
- What are the risk factors for developing breast cancer?
- What is the importance of early breast cancer detection?
- What are the advantages and limitations of mammography?
- How frequently should women undergo mammography and breast examinations?
- What is the risk of radiation with repeated mammography screening over the years?
- Are there any controversies in the area of breast cancer screening?
- How helpful are BRCA1 and BRCA2 genetic tests in identifying women at risk?
- What is the link between estrogen and breast cancer?
- What are breast cancer prevention treatments?
- Are there other breast cancer prevention measures?
What are the advantages and limitations of mammography?
Mammography is an X-ray examination of the breast that has the ability to detect a cancer in the breast when it is quite small, long before it may be felt by breast examination. Approximately 85%-90% of all breast cancers are detectable by mammography. Early detection by mammography has reduced the mortality rate from breast cancer by 20%-30% in women over 50 years of age.
However, some 10%-15% of breast cancers are not visible on mammography but can be felt on physical examination of the breast. Therefore, a normal mammogram does not exclude the possibility of breast cancer. Breast examination by your health care professional by palpation and visual inspection is also important. During a routine physical checkup, a doctor can conduct an examination of the breast.
How frequently should women undergo mammography and breast examinations?
The American Cancer Society (ACS) recommends a baseline mammogram for all women by age 40 and annual mammograms for women 40 and older for as long as they are in good health.
In women with "lumpy breasts" or breast symptoms, and also in women with a high risk of developing breast cancer, sometimes a baseline mammogram at 35 years of age is recommended. This recommendation is somewhat controversial, and there are other viewpoints.
However, the U.S. Preventive Services Task Force (USPSTF) issued new breast cancer screening guidelines in 2009, which recommend against routine mammography screening for women before 50 years of age and suggests that screening end at 74 years of age.
The new USPSTF recommendations are in opposition to other existing breast cancer screening guidelines from organizations such as the American Cancer Society as described above. The USPSTF guidelines also recommend changing the screening interval from one year to two years and suggest that women 40 to 49 years old who are at high risk for breast cancer consult with their doctor regarding the time to begin regular screening mammography.
It is important for women who are concerned about when to begin mammography to discuss the situation with their health care professional. He or she can help you make an informed decision about breast cancer screening that is appropriate for your individual situation.
Mammograms and young women
There is a special issue regarding mammograms in young women. Since young women have dense glandular breast tissue, routine mammograms have difficulty "seeing through" the dense breast tissue. Therefore mammograms may not be able to detect cancer in the breast because the dense breast tissue around the cancer obscures it. However, this problem can be partly offset by the use of special breast ultrasound, which is now an extremely important additional imaging technique used to supplement mammography in difficult cases. Ultrasound can make visible a lump hidden within dense breast tissue. It may also detect lumps and early breast cancers when mammograms fail to identify a problem. Ultrasound can also help doctors locate specific areas in the breast for biopsy (obtain small samples of tissue to study under a microscope). Sometimes doctors also suggest the use of magnetic resonance imaging (MRI) screening (see below) in younger women with dense breast tissue.
Magnetic resonance imaging (MRI) scanning
Recent research has shown that MRI scanning may be a useful screening tool for breast cancer in certain high-risk populations. In 2004, a team of Dutch researchers published a study of over 1,900 women at high risk for breast cancer in the New England Journal of Medicine. These women underwent breast cancer screening that included physical exams every six months along with yearly mammograms and MRI scans of the breasts. While conventional mammography did detect many cancers at an early stage, some tumors were identified by MRI that were not detected by mammography. Overall, MRI led to the identification of 32 tumors, of which 22 were not seen on the corresponding mammogram. Likewise, some tumors appeared on mammograms that were not visible on the MRI scan. Mammography detected a total of 18 tumors, of which eight were not identified by MRI.
The routine use of MRI, however, has many limitations. While it enabled the detection of some tumors in high-risk women, it also detected more noncancerous lesions (false-positives), which lead to many more follow-up examinations and potentially unnecessary medical procedures. In fact, MRI led to twice as many unnecessary examinations and three times as many unneeded surgical biopsies of the breast than screening by mammography alone. MRI is also approximately 10 times more costly (average cost $1000-$1500) than mammography.
Because of these limitations, experts believe that screening with MRI is impractical for women who do not have an elevated risk of developing breast cancer. However, its benefits appear to outweigh its limitations in certain high-risk populations.
In March 2007, the American Cancer Society Breast Cancer Advisory Group issued breast-cancer-screening recommendations that include MRI scanning along with mammography for women 30-69 years of age who are considered to have an estimated lifetime risk of developing breast cancer of 20%-25%.
Adding a yearly breast MRI was recommended for women who
- have a BRCA1 or BRCA2 mutation, indicative of a strong inherited risk of breast cancer;
- have a first-degree relative with a BRCA1 or BRCA2 mutation but have not been tested for the mutation;
- received chest
radiation -- totreat Hodgkin's disease or other cancers, for example -- between10 and 30 years of age.
The guidelines state that there is at present insufficient evidence to recommend the use of routine MRI screening in women with other risk factors, including a personal history of breast cancer, a history of carcinoma in situ or atypical hyperplasia, or dense breast tissue that makes the interpretation of mammograms difficult. Women with these risk factors may want to discuss their screening program with their physician to better determine whether MRI may be useful in their own case.
It is important to note that MRI should not be considered a substitute for regular mammography, and mammography is the only screening tool for which a reduction in mortality (death rate) from breast cancer has been proved.
Breast self-examination and breast examinations by your doctor
Both the American Cancer Society and the USPSTF do not call for regular self-examination of the breasts in their guidelines. The ACS states that breast self-exam is optional, while the USPSTF states that doctors should not teach women to do breast self-examination. The ACS further recommends a clinical breast exam (CBE) by a health care professional about every three years for women in their 20s and 30s and every year for women 40 years of age and over.
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