Breast Cancer Screening: Research and Guidelines

Back in 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 breast self-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.

*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.

Mammograms

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.

Breast Self-Exam

There are 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.

Final Decisions

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.