Government of New Brunswick

1) What is breast density?
Breast density is a measure used to describe the proportion of different tissues that make up women’s breasts. Breasts are made up of fatty (non-dense tissue) and glandular tissue (dense breast tissue), which includes milk glands, ducts and supportive tissue. Dense breast tissue is common and is not considered abnormal. People with high breast density may have increased risk of developing breast cancer.

Women should know what is normal for their breasts and discuss their risk factors for breast cancer (i.e.: personal or family history of cancer, obesity, age, hormone replacement, breast density, gene mutations, etc) or discuss any changes in their breasts with their physician or nurse practitioner.

2) How is breast density determined?
Breast density cannot be detected by a physical exam and it is not related to breast size.

Breast density can only be measured by mammogram. A mammogram is a low-dose x-ray of the breast. It is the most reliable way to find breast cancer early in women.

Breast density is assessed and reported by the radiologist in the mammogram report as:

  • A low breast density result (BI-RADS Category A or B) means you are at average risk for developing breast cancer.
  • The higher the breast density result (BI-RADS Category C or D), the harder it can be to see or detect abnormalities on a mammogram. People with high breast density may have an increased risk of developing breast cancer.

It is important to remember that no screening test is perfect and dense breast tissue can make it harder to detect abnormalities.

3) How can you find out your breast density or mammography results?
As of summer 2020, eligible women aged 50-74 who complete a screening mammogram through the NB Breast Cancer Screening Program will be notified of their breast density with their screening results letter and include an information sheet.

Women less than 50 or older than 74 years of age should contact their physician or nurse practitioner to discuss mammography results, including breast density.

To obtain copies of your report, contact the health records department at the facility where the mammography was done: