How effective is mammography for breast cancer screening?

Laurie R. Margolies, MD
Diagnostic Radiology
Screening mammography has been shown to save lives! The long-term benefit of screening - even with outdated technique - was recently demonstrated in a landmark study that followed over 133,000 women in Sweden for 29 years. The study's conclusion was that regular screening mammography decreased breast cancer mortality by 31%!

With 2 view mammography, digital mammography and yearly screening, the reduction in breast cancer mortality may be even greater.

We do know, however, that mammography does not find all cancers. Ultrasound, MRI and molecular breast imaging are other imaging tools that can find some of the cancers that are mammographically occult.
Although mammograms are currently the best screening test for breast cancer, they are not perfect and it is important to understand their limitations. Up to 10% of breast cancers do not show up on a mammogram, either because they are located in a part of the breast that is difficult to include in the image or they are hidden by normal breast tissue. Still other breast cancers grow in a way that does not disrupt the pattern of the surrounding normal breast tissue and as a result may not be visible. If you feel a lump but have a normal mammogram, it is important to see your doctor and to have the lump evaluated. Other tests, such as breast ultrasound, are helpful in diagnosing the cause of a breast lump when a mammogram is negative.
Randolph P. Martin, MD
Cardiology (Cardiovascular Disease)
As a Fellow of the ACOG, I am proud that they are advocating for early detection. Nearly 75 percent of women diagnosed with breast cancer are not high-risk and to only screen high-risk women ages 40 to 50 would miss many cases of cancer. Screening mammography has contributed to a reduction in fatal breast cancer cases. In fact, breast cancer diagnosed in younger women is often more aggressive and fatal, so early detection is crucial.
It is also very important for women to be aware of their individual risk for breast cancer. They may be candidates for BRCA1 or BRCA2 gene testing, which might suggest more extensive screening that could lead to early detection.
Overall, I believe women want as much preventive medicine as we can give them. Every woman should discuss preventive care with their OB/GYN at their annual well-woman exam.
Visit for more information on preventive care and screenings.
The goal of screening is to detect cancers at an early stage, before they are palpable or detectable by physical exam and before they have spread. Mammography is the gold standard of breast screening. In use for over thirty years, mammography involves a series of x-rays of the breast. Mammography has been proven in randomized controlled trials to produce statistically significant reductions in death, and women over age 40 should have a screening mammogram every year.  
While some women are concerned that the radiation used for mammography might increase the risk of breast cancer, studies involving thousands of women have found the risk of dying of breast cancer significantly decreases for women over 50 who undergo mammography, and there is no evidence that the amount of radiation administered by mammography can actually cause cancer. Mammography is also recommended for most women who have suspicious breast lumps. The probability that a lump contains cancer can be estimated, but a biopsy is needed for certain diagnosis.

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Important: This content reflects information from various individuals and organizations and may offer alternative or opposing points of view. It should not be used for medical advice, diagnosis or treatment. As always, you should consult with your healthcare provider about your specific health needs.