Breast density and breast cancer risk

Having dense breasts is one of the risk factors for developing breast cancer.

To understand your risk, it’s important to consider breast density with other risk factors. This can help you:

• estimate how likely it is you may develop breast cancer
• understand the best action to take on screening and management.

Breast density can be measured on a scale from Type A (low density) to Type D (very dense). Sometimes this is shown as Level 1 to Level 4. We explain the levels at Know your breast density.

The risk is higher in people with breast density levels C and D than women with fattier breasts.

Breast density should be considered with other risk factors, such as:

• family history
• the age of diagnosis of other family members.

It is important to know that:

• Many people with high breast density do not develop breast cancer.
• Many people who do not have dense breasts still develop breast cancer. This is why regular screening is important for all women aged 50 to 74, with any level of breast density. Mammograms are not recommended for men due to the low rates of male breast cancer.
• Only about 10% of women have extremely dense breasts (Type 4 on the BI-RADS scale). For most women, their breasts are in the middle of the scale, where the level of risk from mammographic density is not as high.
• A person’s mammographic density can vary at different points in their life. It’s likely to be:
  • higher in young women and in postmenopausal women taking hormone replacement therapy
  • lower in women who have had children or are postmenopausal.

Assess your breast cancer risk with iPrevent

iPrevent is an online tool from the Peter MacCallum Cancer Centre. It can help you:

• assess your breast cancer risk
• get personalised advice about the type and frequency of screening that might be appropriate for you.

If you have a family history of breast cancer, you can read more about Breast cancer in families.