Breast cancer is a disease affecting approximately 2,300 men and 230,000 women annually in the United States.1

While most women are familiar with the term “mammogram,” they may not be aware of what it is, why it is used and when it should be done.

A mammogram is a low-dose X-ray exam used by health care providers to evaluate for abnormalities in the breast not felt by a clinical breast exam, or to evaluate abnormal breast findings.2

You will also see introductions at the end of some sections to any recent developments that have been covered by MNT‘s news stories. Also look out for links to information about related conditions.

Fast facts on mammograms

Here are some key points about mammograms. More detail and supporting information is in the main article.

  • Every year over 200,000 American women are diagnosed with breast cancer.
  • Mammograms can help find breast cancer early, when treatments are more likely to be successful.
  • After increasing for many years, the percentage of women getting mammograms has leveled off over the past decade.
  • Around 203,400 breast cancer deaths have been averted since 1991.
  • Breast cancer death rate: down 34% between 1990 and 2010.
  • Around 66.8% of women in the US 40 years of age and over have had a mammogram within the past 2 years.
  • Of insured women, 29% are not getting their mammograms and of uninsured women, 68% are not getting their mammograms.
  • Results from randomized clinical trials show that screening mammography can help reduce the number of deaths from breast cancer among women ages 40 to 74, especially for those over age 50.
  • False-positive results occur when radiologists decide mammograms are abnormal but no cancer is actually present.
  • Getting a high-quality screening mammogram and having a clinical breast exam on a regular basis are the most effective ways to detect breast cancer early.
  • Talk to your doctor about your risk factors for breast cancer and the screening plan that is best for you.
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Mammograms can be used for two reasons – to screen for or diagnose a breast abnormality, and are used in women with and without symptoms.1-3

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A mammogram can help a health professional decide whether a lump in the breast is a gland, a harmless cyst, or a tumor.

When used for screening purposes, mammograms are utilized by health care providers to evaluate women who do not display symptoms or abnormal findings with the goal of detecting cancer prior to the onset of clinical symptoms.1-3

These mammograms may also locate calcium deposits referred to as microcalcifications, which may be related to breast cancer.1,2

Diagnostic mammograms on the other hand, are used to evaluate abnormal findings such as a lump, pain, skin changes, nipple thickening, nipple discharge, change in breast size or change in size of an existing lump.1-3

Diagnostic mammograms are also used to further evaluate abnormal screening mammogram findings or when a screening mammogram cannot adequately view the breast tissue, for example, when breast implants are present.1

The goal of a mammogram is to find cancer, however, other findings may be discovered during the test. Some possible mammogram findings include:2,3

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A mammography technician is trained to operate radiologic equipment used to examine breasts for cancer and other abnormalities.
Lumps or masses

The radiologist will evaluate the shape and contour of these findings to determine a suspicion for cancer versus a benign mass. Benign masses generally appear smooth and round with a clearly defined border whereas cancerous masses appear more irregular with a jagged border.


A calcification (seen as white spots on a mammogram) is a calcium deposit often caused by cell secretions, cell debris, inflammation and trauma.

There are two types of calcification – macrocalcifications and microcalcifications:

  1. Macrocalcification: these calcium deposits are large, often due to normal aging and are usually not cancerous
  2. Microcalcifications: very small deposits of calcium, which may be associated with cancer; they are generally found in areas where there are rapidly dividing cells.

Distorted tissue, dense tissue or new breast densities

Dense areas represent areas of the breast tissue that have more glands than fat. Masses and calcifications in these areas are challenging to identify; areas such as this may at times be representative of cancer, with distorted areas being possible spread to other surrounding tissue.

As with any test, mammograms have both benefits and certain risks or limitations. The obvious benefit to obtain a screening mammogram is to detect cancer early prior to it metastasizing or spreading to other parts of the body.1

In combination with a mammogram, the best way to detect breast cancer is to have a clinical breast exam, which is performed by your health care provider.1,2

Several studies discuss that in women ages 40-74, most notably women over age 50, screening mammograms can reduce breast cancer deaths. However, studies did not reveal any benefit in obtaining screening or baseline mammograms in women under the age of 40.1

The risks or limitations of mammograms include:1-3

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Although the compression from the plates on the mammogram machine can feel uncomfortable and even painful for some women, it is needed to get a good picture and only lasts the few seconds needed to take the X-ray.
  • Accuracy: mammograms are not always correct and accurate, and many produce false positive or negative results. Often, this is due to radiologist technique, experience and skill, breast density and age. Most commonly young women, those with a history of prior breast biopsies, family history of breast cancer or those taking estrogen hormone therapy will have false positive results. High breast density, particularly in younger women, is the main cause of false-negative results
  • Overdiagnosis and overtreatment: screening mammograms can not only find cancers and ductal carcinoma in situ (DCIS) that require treatment, but can also find cancers and DCIS that will never become a cause for a woman to experience symptoms or jeopardize her health, which in turn leads to treatment of a cancer that would have otherwise not required treatment
  • Need for additional testing: at times, in approximately 10% of mammograms, additional testing may be required for further evaluation. Additional tests include ultrasound and biopsy. It is important to note that not all abnormal mammogram findings are cancer
  • Not all cancers are diagnosed on screening mammogram: one in five female cancers are missed on a mammogram and may be related to size and or location of cancer
  • Not all cancers found can be cured
  • Low-dose radiation exposure: while the exposure to radiation is low, repeated exposure to radiation can potentially cause cancer. Speaking with your health care provider about your particular risks is important. For the majority of women, the benefits of mammograms outweigh the risk of radiation exposure.

It is important to speak with your health care provider about when it is recommended for you to begin cancer screening with a mammogram, as there is no agreement on when women should begin and receive mammograms.2,3

The United States Preventative Services Task Force (USPSTF) currently recommends that women who are between the ages 50-74 undergo testing with a mammogram every 2 years. They also recommend that women under the age of 50 discuss the need for earlier testing with their health care provider.2

The American Cancer Society, recommends that women begin screening mammograms at the age of 40 and repeat every 1 to 2 years.3

For higher risk women, mammograms may begin earlier and should be determined by your health care provider. In certain high-risk cases, magnetic resonance imaging (MRI) may be recommended in conjunction with mammograms.3

Women who have breast implants need to continue to receive mammograms, which should be discussed with a health care provider. When getting a mammogram, it should be discussed with the mammogram technologist and facility that implants are present.2

It is important to note that performing a breast self-exam will not replace the need to undergo a mammogram and a clinical breast exam performed by your health care provider.1,2

Recent developments on mammograms from MNT news

Women with dense breasts may not need additional cancer imaging

Many women with dense breasts do not need to have additional imaging carried out for breast cancer after having a normal mammogram, according to the findings of a new study.

Anxiety over false-positive mammogram results is ‘only temporary’

Receiving news that a mammogram result is positive is understandably alarming, but receiving a false-positive result can also induce anxiety. However, researchers publishing in JAMA Internal Medicine say women’s anxiety over such false-positive results is temporary and does not negatively impact a woman’s well-being overall.

New guidelines for breast cancer screening age

Women should have the opportunity to begin annual screening for breast cancer from age 40 and also be allowed to continue screening annually after 55, according to the American Cancer Society’s new breast cancer guidelines, published in JAMA.