Mammography is an X-ray of the breast that is considered to be the gold standard for breast cancer screening. It is designed to detect early stage breast cancer in women experiencing no symptoms and to detect and diagnose breast disease in women experiencing symptoms such as a lump, pain or nipple discharge. Unlike film-based mammography, the images produced by digital mammography are available instantly, without the need to ‘re-take’ images due to over- or under-exposure.

Although various medical organizations disagree on when to begin screening mammography and at what intervals, all agree that screening mammography is beneficial, and that women who have screening mammograms die of breast cancer less frequently than those that do not have mammograms. Current screening data shows that yearly screening beginning at age 40 saves 71% more lives than screening every two years and beginning at age 50, as recommended by the United States Preventive Services Task Force (USPSTF) in 2009.

The following organizations recommend annual mammography screening beginning at age 40 for average risk women:

  • American College of Radiology (ACR)
  • American Congress of Obstetricians and Gynecologists (ACOG)
  • National Cancer Consortium Network (NCCN)
  • Society of Breast Imaging (SBI)

The following organizations recommend the decision to start screening should be an individual one. Women who place a higher value on the potential benefit and the potential harms may choose to begin screening at the following ages:

  • American Academy of Family Physicians (AAFP): Ages 40-49, then every other year at and after age 50.
  • United States Preventive Services Task Force (USPSTF): Ages 40-49, then every other year at and after age 50.
  • American Cancer Society (ACS): Ages 40-44, then yearly from age 45-54, then every other year after age 55.
  • American College of Surgeons: Ages 40-44, then yearly from age 45-54, then every other year after age 55.

Terminology for self-exam is evolving, and may now be referred to as “breast awareness”. A minority of breast cancers continue to be detected as a palpable lump rather than by mammography. Breast cancers may also present with breast changes of skin redness, pain, itching, or a bloody or clear nipple discharge. The USPSTF and AAFP recommend that providers should not teach breast self-exam. In contrast, the ACS and NCCN encourage breast awareness, stating that women should be familiar with how their breasts normally look and feel, and report any changes to a health care provider right away. OCOG and NCCN recommend an annual clinical breast exam after age 40, and NCCN recommends a clinical breast exam from 25-39 years of age every 1-3 years.

In 2017 Colorado enacted a breast density notification law that requires that each patient that receives a mammogram be notified of their breast density. AMIC radiologists include this information on each mammography report, and in a letter mailed to the patient with her mammography results and breast density.

There are four categories of normal breast density:

  1. Almost entirely fat – breasts are almost entirely composed of fat. 1 in 10 women
  2. Scattered fibroglandular densities – scattered areas of dense tissue, but the majority of the breast is not dense, 4 in 10 women have this result.
  3. Heterogeneously dense – there are some areas of non-dense tissue, but the majority of the breast tissue is dense, 4 in 10 women have this result.
  4. Extremely dense – nearly all of the breast tissue is dense, 1 in 10 women.

Having heterogeneously dense or extremely dense breasts increases your risk for breast cancer. It also increases the likelihood that breast cancer may go undetected by a mammogram, since the dense breast tissue can mask a potential cancer. Despite concerns about detecting cancer in dense breasts, mammograms are still effective.

If you have been informed that you have dense breast tissue, then you should strongly consider supplemental screening for breast cancer using breast 3D tomosynthesis.

Breast cancer screening recommendations as a whole are unfortunately complicated and without a unified message amongst health professional organizations. This has occurred because it is a complicated topic, and because a public health researcher views breast cancer screenings from a different perspective than a breast oncologist, a breast radiologist, a cancer society, or a family physician. If all perspectives were compiled together, then a recommendation might be:

If you desire to reduce the chance that you will die of breast cancer, and you accept that this may involve some anxiety and stress, then having a screening mammogram every year beginning at age 40 is your best choice. No other method of screening the breast, interval of screening, or age to start screening has better overall effectiveness.

About 5-10% of breast cancers are hereditary, meaning that they are passed on from a parent with a gene defect. The most common hereditary breast cancer is the mutation in the BRCA1 or BRCA2 gene. A woman with the BRCA1 or BRCA2 gene mutation has about a 7 in 10 chance of getting breast cancer by age 80. There are other gene mutations that can lead to inherited breast cancer. Genetic testing may be indicated for patients with an appropriate family history of cancer, but consultation with a genetics counselor or health provider is recommended first to weigh the pros and cons.

The amount of radiation women receive from annual mammograms does not increase their likelihood of developing thyroid cancer (ACR and SBI). A thyroid shield is unnecessary.

To receive a free online estimate of your breast cancer lifetime risk, go to:, or discuss other methods for determining your lifetime risk number with your health care provider. If you have a greater than 20% lifetime risk for breast cancer then the American Cancer Society recommends that you have an annual screening MRI in addition to a screening mammogram. Yearly mammograms and breast MRI begin earlier than 40 years of age in some patients who are at high risk for breast cancer. All high risk patients should consider counseling in a breast cancer high risk clinic to define the appropriate breast cancer screening algorithm.

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