Breast Density Measurement and Reporting for Health Professionals
What is breast density?
Mammographic (breast) density is a term that refers to the relative amount of dense breast tissue (glandular and connective tissue), which appears white on a mammogram, compared with non-dense fatty tissue, which appears dark. Women with high breast density have more fibroglandular tissue and less fatty tissue.
Breast density cannot be determined by the look and feel of a woman’s breast or through physical examination. It can only be measured from a mammogram.
How is breast density measured?
Breast density may be measured by software or observed by a radiologist or breast specialist who read mammograms. Each state and territory BreastScreen Program has or will have its own policies on measuring and reporting breast density and how GPs will be notified.
The BreastScreen Australia Programs that currently measure, and report breast density are listed below. For more information on breast density measuring and reporting for GPs in these state and territory Programs please visit the links:
- BreastScreen South Australia
- BreastScreen Victoria
- BreastScreen Western Australia
- BreastScreen New South Wales
This list will be updated as jurisdictional BreastScreen Programs introduce measuring and reporting.
BreastScreen Australia is working to implement the measurement and reporting of breast density in each jurisdiction through a phased approach. Information on your local BreastScreen Program is available through the state and territory websites:
Why is breast density important?
BreastScreen services in several states are now providing information to women about their breast density in their mammogram result. Patients will be advised to consult their GP to discuss concerns about their breast cancer risk.
The higher the level of breast density, the harder it can be to detect cancers on a mammogram. This is because fibroglandular tissue and cancers both appear white on a mammogram, making the test less sensitive.
High mammographic density is also associated with an increased risk of breast cancer, though this may be small in absolute terms.
Breast density needs to be considered in the context of a patient's overall risk of breast cancer. Breast cancer risk is highly variable; other risk factors include family history, genetic predisposition, previous breast biopsy, hormone replacement therapy use, menopausal status, height, weight and lifestyle factors
What should GPs do with breast density information?
BreastScreen Australia recommends women aged 50 to 74 have a mammogram every 2 years, regardless of breast density. Mammography still detects the majority of cancers and remains the imaging modality for population-based screening for women of all breast densities.
Presently, there is no consensus on the optimal pathway for those with increased breast density, in part because what is appropriate for any individual woman will depend on other risk factors, as well as personal circumstances and preferences. More evidence is required to inform current and future practice however a patient’s knowledge of their breast density enables shared decision-making about breast cancer screening with their healthcare teams.
GPs should consider high breast density in the context of a woman’s overall risk for breast cancer including other risk factors such as age, family history, genetic predisposition, and previous invasive breast cancer; and modifiable risk factors such as diet, alcohol intake, menopausal therapy, and exercise. Using a validated risk assessment tool such as iPreventTM or the Tyrer-Cuzick Risk Assessment Calculator or CanRisk can be used to calculate the patient’s individual risk of developing breast cancer and provide the basis for discussions between women and their doctors about breast cancer prevention and screening. These risks tool may be most useful for women with a moderate risk family history and/or BI-RADS (d) to determine eligibility for Magnetic Resonance Imaging (MRI) Medicare rebates.
What other additional imaging could be used for women with dense breasts?
- Digital breast tomosynthesis (DBT)
- Ultrasound (US)
- Contrast enhanced mammography (CEM)
- Magnetic resonance imaging (MRI)
MRI and CEM are more accurate tests to detect breast cancers that may be masked due to breast density. However, they are not universally available in Australia. DBT and US are more widely available alternatives but are less sensitive tests and have higher false positive rates.
These additional imaging tests may be useful. Currently, additional imaging is only available outside of the BreastScreen Australia Program following consultation and referral by a GP to a diagnostic imaging service. Additional imaging may incur out of pocket costs.
Some of these tests can be covered under the Medical Benefits Schedule (MBS) for eligible patients. Some women at high risk, calculated using a breast cancer risk assessment tool, are eligible for a breast MRI under MBS item 63464, noting that this requires referral from a breast specialist.
GPs are encouraged to discuss with their patient how their breast density affects their chosen approach to breast cancer screening and how to manage and reduce their risks of breast cancer.
While more evidence is required to inform clinical guidelines for women with high breast density, work is underway to develop best practice guidance to support discussions between GPs and their patients.