Breast Cancer Screening & Early Detection
For women at average risk, regular mammography is the primary screening test for breast cancer. Major medical organizations agree that screening beginning around age 40 can reduce the risk of dying from breast cancer, although they differ about how often screening should be performed and when it should stop.
Women at higher risk because of certain genetic mutations, a strong family history, previous chest radiation, or other factors may need earlier screening and breast MRI.
Dense breasts also deserve attention. Dense tissue increases breast cancer risk and makes cancers more difficult to see on a mammogram. But having dense breasts does not automatically mean that MRI or ultrasound is necessary.
The best screening plan isn't necessarily identical for every woman.
When Should Mammograms Begin?
Recommendations differ.
U.S. Preventive Services Task Force (USPSTF): Mammography every two years from ages 40 through 74.
American Cancer Society (ACS): Women 40–44 may choose annual screening; women 45–54 should have annual mammograms; beginning at 55, women may switch to every two years or continue annually.
American College of Radiology (ACR): Annual mammography beginning at age 40 for women at average risk.
Why the disagreement?
Starting earlier and screening more frequently can detect additional cancers, but it also results in more false positives, additional imaging, biopsies, and overdiagnosis.
Overdiagnosis occurs when screening finds a cancer that would never have caused a health problem during a woman's lifetime. Because doctors cannot always determine which cancers will progress, some women may receive treatment they would not have needed.
The question isn't whether mammography can detect breast cancer. It is how much screening provides the best balance of benefits and harms.
When Should Mammograms Stop?
There is no universally agreed stopping age.
The USPSTF recommends screening through age 74 and says there is insufficient evidence to determine the balance of benefits and harms after 74.
The American Cancer Society recommends continuing mammography as long as a woman is in good health and expected to live at least another 10 years.
For women in their late 70s and 80s, overall health becomes particularly important. The decision can take into account life expectancy, breast cancer risk, previous screening, and whether a woman would want treatment if cancer were found.
Dense Breasts: MRI or Ultrasound?
Dense breast tissue both increases breast cancer risk and makes mammograms less sensitive.
Breast MRI is more sensitive than mammography and is generally recommended in addition to mammography for women at high risk, including some women with BRCA mutations or a lifetime breast cancer risk of about 20% or greater.
Breast ultrasound can sometimes detect cancers hidden by dense tissue, but it also produces more false positives and biopsies.
For women whose only additional risk factor is dense breasts, the benefit of routinely adding MRI or ultrasound remains uncertain.
The more useful question is not simply “Do I have dense breasts?” but “What is my overall breast cancer risk?”
What About 3D Mammography?
3D mammography, or digital breast tomosynthesis, creates a more detailed view of breast tissue from multiple X-ray images.
Compared with traditional 2D mammography, it can detect somewhat more cancers and may reduce callbacks for additional imaging. It can be particularly useful for women with dense breasts, although cancers can still be hidden by very dense tissue.
Both 2D and 3D mammography are effective screening methods.
The Most Important Question
Breast cancer screening isn't simply a choice between “mammograms or no mammograms.”
The more useful questions are:
When should I start? How often should I be screened? What is my individual risk? Do I have dense breasts? And at my age and state of health, am I still likely to benefit from screening?
The answers may be different for different women.
Learn More
Current recommendations on when to begin mammography, screening frequency, older women, and dense breasts.
A useful overview of mammography, screening benefits and harms, and screening for women at higher risk.
Explains breast density, how it affects breast cancer risk and mammography, and the questions surrounding supplemental screening.
Recommendations for women at average risk and women at high risk, including the use of breast MRI.
A thoughtful argument that women should be given clear information about both the benefits and harms of mammography so they can make an informed choice about when to begin screening.
A more skeptical perspective on routine mammography, emphasizing absolute mortality benefit, false positives, overdiagnosis, overtreatment, and informed individual choice. Updated July 2021.
Video
A video series examining the benefits and harms of mammography and the evidence behind screening recommendations.