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Dense breast tissue: What it means to have dense breasts

How does dense breast tissue affect breast cancer screening? Content What is dense breast tissue? How do doctors determine if you have dense breast tissue? What causes dense breast tissue? Why does breast density matter? What tests are recommended for breast cancer screening? Are other tests more effective?

Are other tests more effective?

There's some evidence that additional tests may make it more likely that breast cancer is detected in dense breast tissue. But additional tests carry additional risks, and no additional testing method is proved to reduce the risk of dying of breast cancer.

You and your doctor may consider additional or supplemental testing based on your other risk factors and your personal preferences.

Supplemental tests for breast cancer screening may include:

  • 3-D mammogram (breast tomosynthesis). Tomosynthesis uses X-rays to collect multiple images of the breast from several angles. The images are synthesized by a computer to form a 3-D image of the breast. Many mammogram centers are transitioning to incorporate 3-D mammograms as part of the standard mammogram technology.
  • Breast MRI. MRI uses magnets to create images of the breast. MRI doesn't use radiation. Breast MRI is recommended for women with a very high risk of breast cancer, such as those with genetic mutations that increase the risk of cancer.
  • Breast ultrasound. Ultrasound uses sound waves to analyze tissue. A diagnostic ultrasound is commonly used to investigate areas of concern discovered on a mammogram.
  • Molecular breast imaging (MBI). MBI, also known as breast-specific gamma imaging, uses a special camera (gamma camera) that records the activity of a radioactive tracer. The tracer is injected into a vein in your arm. Normal tissue and cancerous tissue react differently to the tracer, which can be seen in the images produced by the gamma camera. MBI is performed every other year in addition to an annual mammogram.

Every test has pros and cons. While each test is proved to find more breast cancers than a mammogram, none of these newer imaging tests is proved to reduce the risk of dying of breast cancer, as has been done with the standard film mammogram.

Supplemental screening test Pros Cons
3-D mammogram
  • Estimated to detect about 1 additional cancer per 1,000 women
  • Done at the same time as a standard mammogram
  • Reduces the need for being called back for additional testing of areas of concern that aren't cancer
  • Helpful in evaluating dense breast tissue
  • Exposes you to additional radiation, though levels are still very low
  • Availability is becoming more common
Breast MRI
  • Estimated to detect about 14 additional cancers per 1,000 women
  • No additional radiation exposure
  • Widely available
  • Likely to find areas of concern that aren't cancer, but that require additional imaging or a biopsy
  • Requires injection of contrast material
  • Expensive test that might not be covered by insurance unless you have a very high risk of cancer
Breast ultrasound
  • Estimated to detect an additional 2-4 cancers per 1,000 women
  • No additional radiation exposure
  • Widely available
  • Likely to find areas of concern that aren't cancer, but that require additional imaging or a biopsy
  • Quality of exam dependent on experience of person doing the test
Molecular breast imaging
  • Estimated to detect about 7 additional cancers per 1,000 women
  • Less likely to find areas of concern that aren't cancer
  • Involves injection of a radioactive tracer, which exposes you to a very low level of radiation
  • Available at few medical centers

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