If you’ve recently had a routine or screening mammogram, your report may now include a breast density result. This is a new addition for many women, and it naturally raises questions.

In this article, we’ll cover the top 10 most common questions women have about breast density.

1. What Is Breast Density, and What Do BI-RADS Categories A–D Mean?

Your breasts are made up of a mix of fatty tissue, glandular tissue, and connective tissue. Breast density describes the balance between these components, scored using the international BI-RADS scale (5th edition):

    • Category A — almost entirely fatty tissue

    • Category B — scattered areas of dense tissue

    • Category C — heterogeneously dense; the mix of tissue can hide small abnormalities

    • Category D — extremely dense; this significantly reduces how well a mammogram can see through the tissue

Categories C and D are considered high breast density — a common, normal anatomical variant affecting roughly 40–50% of Australian women. It is NOT a disease or an abnormality, simply a description of what your breast tissue looks like on a mammogram.

2. What Is a Volumetric Breast Density (VBD) Score?

Most Australian radiology providers no longer rely on visual estimation alone. Instead, they use automated software (commonly Volpara) to calculate the precise percentage of dense tissue in your breast:

    • Category A: VBD < 3.5%

    • Category B: VBD < 7.5%

    • Category C: VBD < 15.5%

    • Category D: VBD ≥ 15.5%

3. Can My Doctor or I Feel Dense Breast Tissue on Examination?

No. Breast density is a mammographic finding only. It has no connection to how your breasts look or feel — their size, firmness, or texture on self-examination or clinical exam tells you nothing about their density on imaging.

4. Why Does Breast Density Matter? Understanding the “Masking Effect”

On a mammogram, fatty tissue appears dark and dense glandular tissue appears white — the same colour as most breast cancers. In dense breasts, this overlap can allow a small tumour to be camouflaged by surrounding tissue, known as the masking effect.

According to the 2025 national GP guidance from BreastScreen Australia, mammogram sensitivity falls from around 90% in low-density breasts (Category A or B) to approximately 84% in Category C, and to around 64% in Category D.

5. Does Breast Density Increase My Cancer Risk?

Yes. High breast density is independently associated with a higher relative risk of developing breast cancer. The 2025 national guidance reports that, compared with the general population baseline (Category B breast density):

    • Category C density carries roughly 1.6 times the risk

    • Category D density carries roughly 2.6 times the risk

That said, density should never be assessed in isolation — it’s one of several factors, alongside age, lifestyle, and family history, that together determine your overall breast cancer risk.

6. Can I Reduce My Breast Density Naturally?

Not directly. Your baseline density is largely determined by genetics. It does change with age: as hormone levels fall, particularly after menopause, dense glandular tissue naturally converts to softer fatty tissue. A healthy lifestyle lowers your overall cancer risk, but it won’t meaningfully change your density category.

7. Do I Need Further Imaging?

Not automatically — it depends on two things:

✅ Screening versus symptomatic assessment. If you have a new symptom — such as a breast lump or nipple discharge — more advanced imaging such as breast ultrasound, MRI, or contrast-enhanced mammography may be appropriate.

✅ Your individual breast cancer risk. At average risk (population risk is around 11–12%), no additional imaging is routinely required. At moderate risk (20–30%) or high risk (>30%), supplemental imaging such as MRI or CEM may be of benefit. Click here for more information on how to estimate your breast cancer risk.

8. What Are Contrast-Enhanced Mammography (CEM) and Breast MRI?

For women with high density and other risk factors, national guidance identifies advanced supplemental imaging as the most effective way to overcome the masking effect:

    • Contrast-enhanced mammography (CEM): an iodine-based dye is injected before the mammogram to highlight areas of abnormal blood flow. There is currently no MBS item number for CEM used as supplementary screening after a BreastScreen mammogram, so it is generally self-funded.

    • Breast MRI: uses magnetic fields to produce highly detailed three-dimensional images of the breast, without radiation.

9. Will Medicare Cover a Breast MRI for Dense Breasts?

High density alone does not qualify an asymptomatic patient for a Medicare-subsidised breast MRI. To be eligible for the MBS rebate (Item 63464), you need to meet certain criteria, e.g.:

    • You are under 60 years of age

    • Your calculated lifetime risk exceeds 30% (or your 10-year absolute risk exceeds 5%), using a validated risk assessment tool such as iPrevent

10. What Should I Do If My Report Shows High Density?

A Category C or D result is not a reason to panic — it’s a prompt for a conversation, not a diagnosis. The best next step is a routine appointment with your GP for a shared decision-making discussion.

Your GP can review your mammogram result and estimate your personal breast cancer risk using a validated Australian tool such as iPrevent.

🔹 If your risk is low — routine two-yearly screening mammography continues as normal.

🔹 If your risk is higher — your GP may refer you to a breast surgeon to discuss the pros and cons of genetic testing and to develop a personalised screening plan.

🔹 If you carry a known high-risk genetic variant (such as BRCA1/2) — referral to a specialised high-risk clinic, such as the RAH High Risk Breast Clinic, provides access to an established, tailored screening program.

For more information, see the Breast Density GP Guidance, published in November 2025 by the Australian Government Department of Health, Disability and Ageing, together with BreastScreen Australia.

The Golden Rule of Breast Awareness

Regardless of your density category, or how recent your last clear screen was — if you notice a new lump, skin dimpling, nipple changes, or unusual discharge, don’t wait for routine screening. See your GP promptly for a diagnostic referral.

Disclaimer: This article is for general information only and is not a substitute for professional medical advice. Always consult your GP or breast specialist for guidance specific to your circumstances.