RANZCR has argued that women should be notified, but with no guidelines in place, what can GPs do?

Debate about whether to tell patients their breast density has raged since RANZCR released a position statement late last year recommending mandated reporting.

Currently, Western Australia and South Australia are the only states where BreastScreen notifies people identified as having dense breasts on screening mammograms—but that looks likely to change.

BreastScreen Australia’s current position statement was published in 2020 and does not support routine recording of breast density until more evidence about how to assess and manage it emerges— but this statement is currently under review, with the updated draft expected to be released mid this year.

Dr Melissa Bochner, a breast surgeon and Head of the Breast Endocrine Unit at Royal Adelaide Hospital said the updated statement is expected to align with RANZCR, meaning more women are likely to be informed of their breast density.

But where does that leave GPs?

Without evidence-based guidelines for management, Dr Bochner says it will be crucial to help women understand their overall breast cancer risk without causing undue alarm – and to help them make informed decisions about screening.

A bit of background about breast density

Also known as mammographic density, breast density refers to the ratio of fibroglandular tissue to fatty tissue on a mammogram.

It is commonly described using the American College of Radiology’s Breast Imaging Reporting and Data System (BI-RADS) under four categories ranging from ‘A’ (mostly fatty) to ‘D’ (extremely dense).

High breast density is more common in younger women, with BreastScreen NSW reporting that approximately 40% of women in their 50s and 25% of those aged 60 and over have dense breasts.

High breast density is both a risk factor for breast cancer and a determinant of reduced sensitivity of standard mammography.

The argument for telling women their breast density

Women with high breast density have an increased risk of developing breast cancer. Recent research found that extreme breast density (BI-RADS category D) is associated with a 2.1-fold increased breast cancer risk compared to the average for BI-RADS category B.

At the same time, the masking effect of dense breast tissue makes mammograms harder to read and reduces mammographic sensitivity for cancer detection, which can lead to underdiagnosis, Dr Bochner says.

RANZCR’s statement notes that breast cancer is the leading cause of cancer in Australian women, arguing for mandated breast density reporting while a risk-based model for breast cancer screening is being developed.

Evidence suggests most women would like to know, with 90% of respondents in a 2022 BreastScreen SA survey saying they want to be informed of their breast density, compared to just 2% who said they’d prefer not to be told.

Another 2022 qualitative Australian study found the majority of women supported the idea of breast density notification, with many suggesting they had a ‘right to know’.

Some evidence also suggests that women who know their breast density and feel better informed are more likely to undergo screening mammography. And a 2020 study found women who knew their breast density were more likely to know that higher breast density (and hormone replacement therapy after menopause) are breast cancer risk factors.

The arguments against notifying women

A key argument against telling women their breast density is that it may adversely affect their mental wellbeing. A 2022 RCT involving 1420 Australian women found that compared to the control group, women who were notified of their breast density following screening mammography were significantly more likely to feel anxious, confused and worry about breast cancer. They also reported a significantly higher intention to seek supplemental screening.

In a qualitative 2023 Australian study, over two-thirds (67.9%) of women said they would feel a little to very anxious if told they had dense breasts. Fear of getting cancer was the most common reason.

Meanwhile, “We can’t make people’s breast density lower,” Dr Bochner points out. “It’s not a disease.”

Another problem is that it’s not clear what to do when someone has dense breasts since there are no clear data or guidelines.

‘Patients have a right to information about their bodies’

Despite all this, Dr Bochner believes women should be told.

“I think that people do need to be informed about the results of their tests. It’s information about that patient’s body, that patients should be aware of.”

“They need to know if they’ve got very high breast density that mammographic sensitivity is lower, especially if they’ve got a lump.”

“Then the obvious question is ‘What am I going to do about it?’”

Supplemental Screening

Dr Bochner recommends supplemental screening for women at increased risk, with options including breast tomosynthesis, contrast enhanced mammography, and breast MRI.

Again though, there are no clear data or guidelines for supplemental screening, so you’ll need to weigh up pros and cons such as sensitivity, specificity, cost, radiation, availability, and patient preference, Dr Bochner says, adding that shared decision-making is particularly useful in this context.

It’s also crucial to remember that breast density is only one of many breast cancer risk factors and to know how to calculate breast cancer risk, Dr Bochner adds.

She suggests using either the Tyrer-Cuzick Risk Assessment Calculator or iPrevent to do this, stressing they have some important differences that can guide your choice.

“The calculators ask different questions and are weighted towards different risk factors,” she explains. “The Tyrer-Cuzick uses breast density in the risk calculation whereas the iPrevent does not. The iPrevent has got more family history … and it asks about lifestyle factors such as exercise and alcohol.”

“So we need to have a little think about what it is that we’re trying to tell a patient. Are we concerned about their breast density, in which case we probably need to run the one that includes breast density. Are we more concerned about patient lifestyle risk factors, in which case iPrevent may be more appropriate, particularly if I want to reassure people.”

Completing these tools can take considerable time, she adds, so you might want to get patients to do it at home and bring their results in to discuss.

Key takeaways:

• High breast density increases breast cancer risk and can mask cancers on a mammogram.
• Evidence suggests most women would prefer to know their breast density and that notification may promote compliance with screening mammography.
• Other evidence shows breast density notification can lead to higher levels of anxiety, confusion, and fear of breast cancer.
• Breast density is just one factor, and GPs can use online tools to calculate overall breast cancer risk.