Breast Cancer Screening: Research and Guidelines
In November 2009, the United States Preventive Services Task Force (USPSTF) released updated guidelines for breast cancer screening. The updates called for changes in well-known current practices for mammograms and breast exams. These changes caught a great deal of media attention and raised public confusion and concern.
Breast Cancer Screening
Breast cancer screening tests are designed to find cancer in people who do not have symptoms. The hope is that finding cancer earlier will prevent cancer deaths. Research has tried to measure how well screening tests are doing this. Current breast cancer screening options include mammograms, breast exam by a healthcare provider, and self breast exam.
The USPSTF is a panel of experts in medicine that reviews research and develops guidelines for disease prevention and screening. The American Cancer Society (ACS) and American Congress of Obstetricians and Gynecologists (ACOG) also provide guidelines for screening. These organizations create their guidelines based on their interpretation of current research.
Below are guidelines from USPSTF, ACS, and ACOG and summaries of current research. These guidelines and evidence summaries are for women with no symptoms or family history of breast cancer.
|.||Age-Based Guidelines for Mammograms in Women||Clinical Breast Exam||Self Breast Exam|
|40-49 years||50-74 years||75 years and older|
|USPSTF||Individualized screening/ No routine screening*||Every two years||No specific recommendation||No recommendations were made||Not recommended|
|ACS||Every year||Every year||No recommendation for age to stop||Every 3 years for women aged 20-39. Every year starting at age 40.||Optional from age 20 on. Women should be informed of potential benefits and harms.|
|ACOG||Every 1-2 years||Every year||No recommendation for age to stop||Every year||Can be recommended despite lack of supporting evidence|
*The USPSTF recommends against telling all women aged 40-49 years they should have mammograms. The decision to start screening every 2 years before the age of 50 years should be an individual one. It should be based on each person’s values regarding specific risks and benefits.
There have been many studies on mammograms, but they were not done perfectly. As a result, experts analyzing the research may reach different conclusions.
For women 40-69 years, regular mammograms appear to reduce the risk of dying from breast cancer. There is little evidence about the benefit of mammogram in women aged 70 years or older.
Studies suggest that screening starting at age 40 provides a small reduction in the risk of dying from breast cancer when compared to starting screening at age 50. No change in the overall risk of dying has been shown. There is also a chance of having abnormal test results that are not cancer. This can lead to unnecessary tests, procedures, and stress.
Here is an example of the effect of mammography for women 40-49 years. If 1,000 women in this age group get a screening mammogram:
- 1 woman will have a cancer that is not seen on the mammogram
- 100 will have an abnormal mammogram. Out of these women:
- 90 will be watched more closely with imaging, but not have a biopsy
- 10 of these women with an abnormal mammogram will have a biopsy (to determine if cancer is present)
- 8 of these women will not have cancer
- 2 of these women will have cancer discovered
Here is an example of the effect of mammography for women aged 50-69 years. If 1,000 women in this age group get a screening mammogram:
- 1 woman will have a cancer that is not seen by the mammogram
- 83 will have an abnormal mammograms. Out of these women:
- 72 will be watched more closely with imaging, but not have a biopsy
- 11 will have a biopsy (to determine if cancer is present)
- 7 of these women will not have cancer
- 4 of these women will have cancer discovered
Clinical Breast Exam (by Healthcare Professional)
There is very little evidence about the clinical breast exam. One study suggests a clinical breast exam may be as helpful as a mammogram.
There are eight studies comparing women who regularly check their breasts and women who do not. These studies all show no effect on the risk of dying from breast cancer. These studies do show an increase in finding lumps that are not cancer. This can lead to unnecessary medical tests, procedures, and stress.
This information can be confusing. Your age, overall health status, and family history of cancer may affect your decision to have screening tests. Discuss the risks and benefits of breast cancer screening specific to you with your healthcare provider.
American Cancer Society
American Congress of Obstetricians and Gynecologists
United States Preventive Services Task Force
DynaMed Editorial Team. Breast Cancer Screening. Last updated 2009 Nov 25. Available from DynaMed: http://www.ebscohost.com/dynamed. Accessed November 25, 2009.
United States Preventive Services Task Force website. Available at: http://www.ahrq.gov/clinic/uspstfix.htm. Accessed November 24, 2009.
Please be aware that this information is provided to supplement the care provided by your physician. It is neither intended nor implied to be a substitute for professional medical advice. CALL YOUR HEALTHCARE PROVIDER IMMEDIATELY IF YOU THINK YOU MAY HAVE A MEDICAL EMERGENCY. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with any questions you may have regarding a medical condition.
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