Dense Breasts and Screening Mammograms

What is breast density?

Breast density are words used to compare the types of tissues in women’s breasts. There are three types of normal tissues in the breast:

  • glandular
  • connective
  • fatty

Breast density compares the amount of glandular and connective tissue with the amount of fatty tissue. Dense breast tissue has more glandular and connective tissue than fatty tissue.

Why is it important for me to know about breast density?

Extremely dense breast tissue can make it harder for the radiologist to read the mammogram because density can cover up an area of cancer. Dense tissue appears white and so does an area with cancer.

The dense breast tissue is also one of several risk factors for breast cancer. Breast density on its own has a small impact on a woman’s overall risk of developing breast cancer.

How do I know if I have dense breasts?

A mammogram is the only way to detect if a woman has dense breasts. Breast density cannot be felt in a physical exam. You cannot tell if a woman has dense breasts based on the size or firmness of her breasts.

On a mammogram image, fatty tissue appears dark. Dense tissue appears as solid white areas. The radiologist reports the breast density on the screening mammogram report.

Who is likely to have dense breasts?

Dense breast tissue is common and normal. It can be an inherited trait or some hormone therapies can increase the density of the breasts.

Younger women usually have breast tissue that is dense. As women grow older, the density usually decreases because breast tissue becomes more fatty. A screening mammogram every year is recommended for all women with dense breast tissue.

What does the Screening Program for Breast Cancer do for women with dense breasts?

If your screening mammogram images show your breast tissue is extremely dense (75 per cent or greater density), you will be invited back the next year for screening mammogram.

Being screened every year will help to detect small changes in the breast and increase the chance of finding any worrisome changes sooner.

What can I do if I have dense breasts?

If you know you have dense breasts, you can talk to your healthcare provider about your personal risk factors and make a plan for your own breast health.

Know the normal look and feel of your own breasts and call your healthcare provider if you notice any changes, even if you just had a mammogram.


Below are images that show how various levels of breast density appear on a mammogram.

Screening Breast Dense Breast Image

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