Tests used to screen for breast cancer
Several tests may be used to screen for breast cancer, with mammography being the standard test for most women. Some of these tests may also be used as part of diagnosing breast cancer.
Mammography
A mammogram is an x-ray picture of the breast. Learn more about mammography, including who should be screened and when, what to expect during a mammogram, and how results are reported at Mammograms.
Breast magnetic resonance imaging (MRI)
Breast MRI uses radio waves, a strong magnet, and a computer to create detailed pictures of the inside of the breasts. It does not involve radiation. If you are at high risk for developing breast cancer you may have breast MRI along with mammography. That is because MRI is more sensitive at detecting cancer than mammography and mammography alone may miss some cancers in high-risk women.
If you have dense breasts you may be offered breast MRI along with mammography. However, it is not known whether additional, or supplemental, screening with MRI leads to better health outcomes in women with dense breasts. Learn more about dense breasts.
Breast ultrasound
Breast ultrasound uses high-energy sound waves to look at tissues and organs inside the body. If you have dense breasts, you may be offered screening with ultrasound in addition to mammography. It is not known whether additional screening with breast ultrasound leads to better health outcomes.
Clinical breast exam
A clinical breast exam is a physical exam of the breast done by a health care provider. He or she will carefully feel the breasts and under the arms for lumps or anything else that seems unusual. A clinical breast exam alone is not an adequate screening test for breast cancer.
Breast self-exam
It is important for all women to be aware of how their breasts normally feel so that they can check with their doctors about any unusual changes. Even if you have recently had a normal mammogram, you should let your doctor know if you feel something unusual. However, breast self-exams are not an adequate breast cancer screening test on their own.
What are the benefits and harms of breast cancer screening?
All cancer screening can have both benefits and harms.
The benefit of breast cancer screening is that finding breast cancer by screening before it causes symptoms means treatment can start earlier and potentially be more effective.
The potential harms of breast cancer screening include:
- False-positive results. False-positive results can cause mental and emotional distress and require additional follow-up procedures, such as biopsies, that can themselves cause harm. False-positive results are more common among younger women, women with dense breasts, women who have had previous breast biopsies, women with a family history of breast cancer, and women who are taking estrogen (for example, menopausal hormone therapy).
- Overdiagnosis and overtreatment. Some cancers found during screening may not have caused problems during a woman’s lifetime and would not have needed treatment. Finding these cancers earlier may not improve someone’s health or help them live longer but will expose them to the harms of treatment.
- Delayed diagnosis. Diagnosis can be delayed due to false-negative results. False-negative results are more common among women with dense breasts. Diagnosis can also be delayed if someone with a recent normal screening test result does not check with their doctor about symptoms that could be from an interval breast cancer.
- Radiation exposure. Radiation from mammography can potentially cause cancer, although the risk is very low.
Learn more about the tradeoffs between benefits and harms of cancer screening in the Cancer Screening Overview.