Breast density advocacy on the rise

15 minute read

If our national cancer screening scheme doesn’t start informing women of their extra risk, it could look outdated and second-rate.

When Krysty Sullivan had a mammogram in 2018, she immediately went overseas on a quick family visit and came home to a set of clear results and she got on with life.

Apart from a weird one-sided back pain that persisted all year, things were going well for her, with a new job she was enjoying. Eleven months later she found a lump in her breast.

In one day she had another mammogram which showed no cancer, followed by an ultrasound which clearly showed two tumours, both over 2cm. She had a biopsy, and two days later the results were in: triple-negative breast cancer.

It was then that Ms Sullivan was told the missing piece of the puzzle – she had extremely dense breasts. It was, in fact, her only major risk factor for breast cancer. She was not a smoker or a drinker. She had had her children by the age of 30, and although she had a grandmother who had been diagnosed with breast cancer young, a genetic test had showed no significant mutations.

After four months of chemotherapy and two surgeries, Ms Sullivan is doing well.

“I am tremendously grateful to have had breast cancer here in Australia,” she says. “The treatment that I got, I felt was world-class, top-notch delivered by really caring people. I am tremendously grateful that BreastScreen exists and that it’s accessible for everyone.”

Dr Sandy Minck is a GP who works these days in medical education and communications. With a family history of breast cancer, and the knowledge that she had “complex, extremely dense breasts” Dr Minck was diligent about regular screening.

In June 2022 she had her routine mammogram and ultrasound which found microcalcifications, with a subsequent post-biopsy diagnosis of atypical lobular hyperplasia.

“There were some decisions to be made,” she says. “I knew that I had extremely dense breasts, although I don’t even think at that time, I fully realised the significance and impact of that.

“I saw a breast surgeon and we decided to do an MRI, which I had to self-fund because I didn’t meet the Medicare criteria and there was an abnormality on the MRI. So I had an excision biopsy, which showed lobular carcinoma in situ.

“That’s not considered cancer in the same way ductal carcinoma is, but it increases your risk up to 10 times.”

Dr Minck is now a couple of months past risk-reducing mastectomy, a procedure she describes as “the best decision I’ve ever made”.

Breast screening

In Australia, if you are a woman age between 50 and 75, you are invited to have a free mammogram every two years at a state BreastScreen facility.

Of course, anyone can get a screening mammogram done privately at any age, and as often as they like, if they are prepared and able to pay for it.

The BreastScreen Australia screening program started in 1991 for women aged 50 to 69, and then expanded to include women aged 70 to 74 from 2013. It’s been incredibly successful but has remained largely unchanged over the decades.

As Ms Sullivan and Dr Minck found out, the BreastScreen program can be problematic for the percentage of the Australian population who have dense breasts.

Why is breast density important?

Associate Professor Wendy Ingman from the University of Adelaide is a researcher on breast cancer risk, and breast density is one of her focuses.

“Breast density is basically what a breast looks like on a mammogram,” Professor Ingman tells TMR.

“Breast density refers to how white or dark the breast appears on the mammogram – low density has more dark areas and less white, and high density has more white and less dark areas.

“The white areas are predominantly fibroglandular tissue, the breast epithelial cells, which are the cells which will make and secrete milk when a woman is breastfeeding, and also the supporting stromal cells around those epithelial cells. 

“By contrast the dark areas are areas of a lot of adipose tissue or fat.”

Having dense breasts both increases a woman’s risk of developing cancer, and the risk of that cancer being missed on a screening mammogram.

“Breast density is an independent risk factor for breast cancer,” says Professor Ingman.

“Women with high density – either heterogeneously dense, or extremely dense breasts – have an increased risk of breast cancer compared to women with lower average density.

“Over time generally as a woman ages, her breast density declines slightly. And her body mass index will also affect her breast density.

“If there’s more fat on a woman’s body, there will also be more fat on her breasts. They will therefore be less dense and more fatty, and BMI is also a risk factor for breast cancer, as is age.”

The risk factor is intrinsic as well as causing cancers to be missed at screening.

“We know there are missed cancers because of high breast density,” says Professor Ingman. “But separately to that, there is also a biological increase in risk in women with high density.

“My research has been focusing on how the immune system affects breast density. What we’ve found is that there is chronic low-level inflammation in breast tissue that’s highly dense and that this chronic inflammation is actually one of the driving factors which increases a woman’s breast cancer risk when she has high density.

“Our immune systems do an amazing job. We’re bombarded constantly with pathogens, viruses. We are protecting our bodies constantly. But that comes at the cost as well, that our bodies cannot always do the perfect thing when it comes to how we interact with our environment.”

Two problems exist for Australian women with dense breasts.

Dense breast notification

The first is finding out whether they have dense breasts in the first place.

In the US, the FDA has recently mandated that breastscreen providers must notify women if they have dense breasts. That doesn’t happen in Australia, except in Western Australia which does tell women as a matter of routine. Two states, Queensland and South Australia, are currently trialling breast density notification in their respective breast screen programs.

BreastScreen Australia, the umbrella organisation overseeing the state screening programs, explicitly does not recommend notification. Its position statement on breast density, which was last updated in 2020, acknowledges that the evidence around additional testing for dense breasts is evolving, but comes to the conclusion that: “BreastScreen Australia should not routinely record breast density or provide supplemental testing for women with dense breasts”.

Professor Vivienne Milch, who is the medical advisor to the Commonwealth Department of Health and Aged Care on screening policy, tells TMR that there will be another evidence review later this year. That position statement was based on the evidence at the time, she says.

“It acknowledged that the evidence base was growing and that BreastScreen Australia would work with researchers and states and territories and the breast screen program to make sure that it was up to date.

“We’re aware of evidence that is evolving. And the plan is for this year, for there be to be an updated evidence review to take place.

“We’re aware of the growing momentum of advocacy and also some women’s desire to know their breast density. We are very aware of that. We’re also aware that various breast screen services in different states have either a different policy or are trialling, or piloting. It’s very important that we see the results of that research.

“BreastScreen will keep abreast of the evidence as it’s developing.”

I have dense breasts. Now what?

The second problem is knowing what to do about them.

Professor Ingman says there is no clear guidance.

“What is emerging is different pathways for management of dense breasts,” she says. “One of them is with ultrasound, which can detect more cancers in dense breast tissue. That is being offered by screening programs in other countries. For example, Canada offers ultrasounds for women with dense breasts.

“There is a problem with ultrasound in that it can increase the rate of false positives.

“The other option is contrast-enhanced MRI. And that’s really the one where we’ve got now some strong evidence.”

One of the strongest pieces of evidence for supplementary screening in women with dense breasts came from a study called The Dense Trial, which was published in the New England Journal of Medicine in November 2019.

The researchers assigned 5000 women aged 50 to 75 with extremely dense breasts and normal mammography results to either receive supplemental MRI or mammography screening only. They found an additional 16 cancers per thousand women screened.

The modelling that then came out of that study suggests that we can save an extra 11 lives per thousand women screened using supplemental screening. Importantly, when those women were then followed until their next screening round, the interval cancers, which become evident between screening rounds, were less than 20%. The rate was reduced by more than 80% in the group who had MRI.

When you consider that mammographic screening, as it stands today, saves eight lives per thousand women screened, an extra 11 is significant.

Supplemental screening

It seems a no-brainer to not only inform women of their breast density, but to then insert supplemental screening – with ultrasound, or MRI – into the national screening program for those women with that increased risk.

But as with all national screening programs, it’s not that simple.

“We always have to remember that this is a population screening program,” says Professor Milch.

“One of the things we have to obviously consider is cost-effectiveness. Another one is equity of access. This [program] is for all Australian women applied systematically to one defined age group.  We need to make sure that we are always considering equity of access. And that’s both in terms of cost and in terms of accessibility geographically, and availability of imaging.

“One of the things that came out of the 2020 position statement is that we need accuracy and reliability of measurement, and we need a clear pathway for knowing what to do if higher breast density is found … which is why the current policy is that breast density is not routinely reported or notified to women participating in the program.

“It comes down to this – yes, the test needs to reduce mortality. We need to make sure that we are reducing mortality from breast cancer, [but also] that we’re reducing morbidity from breast cancer.

“We need to find breast cancers earlier so that the impact of the treatment is less, and we need to improve disease outcomes. 

“But we have to always consider the harms as well. And this is very important in a population-based screening program: we have to reduce the false positives. We also have to reduce false negatives because we don’t want to be reassuring people who actually do have cancer, but we didn’t find it.

“We also have to consider overdiagnosis. Are we finding something that wouldn’t have done that person any harm in their lifetime?

“And then of course we need to consider the other harms of finding something that actually impact on the person’s physical or emotional health.

“All of these things need to be considered and they all need to be tested and validated in the program.”

Do women need to be protected from the truth?

Ms Sullivan and Dr Minck aren’t buying the anxiety argument.

“The days of viewing women as not being capable of handling information and making decisions should be long past – that feels so 1950s to me,” says Ms Sullivan. 

“You’re taking a risk with lots of things in life. Anxiety shouldn’t stop anyone from learning a risk. You can’t decide whether to take a risk or to reduce a risk if you don’t know about it.

“It’s past time that we inform women of risks that involve their health and give them information so that they can make decisions.

“Sitting here knowing this information for decades and not making any progress, to me, it’s really disappointing. People’s lives are at risk.”

Dr Minck agrees.

“I did some further investigation and research [after my diagnosis] and have read BreastScreen Australia’s position statement on breast density. The thing that impacted me most was the focus on anxiety and undue psychological harm if women were notified of their breast density,” she says.

“As a consumer I’m outraged. As a health professional, I’m dumbfounded. I just don’t understand it.”

Where to now?

Professor Bruce Mann is a breast surgeon and researcher at the University of Melbourne. He is the leading breast cancer expert working with ROSA – the Roadmap for Optimising Screening in Australia.

“Screening has worked well,” Professor Mann tells TMR.

“Screening was introduced in Australia in the early 90s. That’s quite a long time ago. At the time the screening technology was rudimentary, two-dimensional mammography. Better than nothing.

“Since then, the screening technologies advanced dramatically and knowledge about breast cancer risk has advanced dramatically. But we’re still in the situation that screening in Australia is aimed at women aged 50 to 75. And that’s it.

“The only risk adjustment that we’re doing is female sex and age over 50. Nothing else. And we’re still doing two-dimensional mammography as screening. Nothing’s moved.

“Why hasn’t it moved? Because we have a program that is recognised as saving lots of lives, reducing lots of morbidity, and you don’t want to put that at risk. You can’t burn the house down and rebuild it. We’ve got to keep living in the house, but we’ve got to update it.”

Professor Mann thinks that, in an ideal world, we should start breast screening younger and find a way of offering supplemental screening to women at higher risk of developing breast cancer because they have dense breasts.

“The young women [under] 50, who come in with stage three or sometimes stage four, but mainly stage two and stage three cancer – they’ve done the right thing. They have not been invited for mammographic screening because we don’t start inviting until 50. They’ve trusted the system and they’ve got this stage three cancer.

“Because it’s more advanced, they need more treatment. The treatment has toxicity. It’s often effective, which is wonderful. But had they been told to get their risk assessed at 35, say, and started screening at 40, using the appropriate modality, they may well have had stage one cancer – five-year survival of 100%.”

It’s a stark reminder that in the end, this isn’t about money, but about saving lives.

“We need an agreed, feasible, acceptable approach to risk assessment,” says Professor Mann.

“It may be that sometime in their 30s, women should have their risk assessed and then sort of put in the bank and say, ‘I’m in the group who don’t need to start screening till 50’, or, ‘I’m in the group who need to start now’.

That risk assesment would include family history, perhaps reproductive history, and mammographic density.

“Those with high density should start [screening] sooner,” he says. “There is a group of women for whom an MRI screening would be better. But MRIs are expensive. There are huge MRI capacity problems.”

But undoubtedly there is a group, he says, for whom some form of contrast imaging – MRI, contrast mammography, or a combination – is needed.

“A rejig of BreastScreens so that they also have magnets or contrast machine – that’s a really big change. And goes back to, what can be introduced? How do you remodel the plane while you’re still flying?”

How it looks

One of the great things about BreastScreen Australia and its state-based programs is the high trust factor.

The danger is that our highly successful national breast screening program will start looking out of date and insufficient for a significant proportion of Australian women.

“As women and the community become more informed there is a danger that what is offered by BreastScreen will be seen as insufficient,” says Professor Mann.

“And then what would happen, what could happen is some of those who know that and can afford it, would opt out [of the screening program].

“What we don’t want in this country is a two-tier system where those who know and can get the best, opt out [and pay for private screening] and everyone else gets what’s offered to them.”

In the end, consumer advocacy and education will win out, but how it wins out is important.

“If you can show that by doing something different, you are finding more cancers, fewer cancers are being diagnosed between screening rounds, and the stage, the size and the nodal status of cancers that are diagnosed is moving in a favourable direction, I believe that’s sufficient to encourage implementation, with a planned review in 10 years when the mortality information’s there,” says Professor Mann.

“Treating very early breast cancer is highly effective, it’s cheap, and the person is not out of action for very long. That scenario compared to a stage three or four diagnosis is actually saving a lot of money. The finances are important, but it needs to be in a holistic way.

“It’s not just the cost of screening. Because downstream, there will be financial implications to the health system and to the overall economy.”

The last word goes, appropriately, to a patient.

“There is a gap,” says Ms Sullivan.

“BreastScreen was set up some 30 years ago and it took into consideration the risks at that time. It hasn’t changed very much since then.

“To think that there’s a one-size-fits-all screening with what we know, to me, isn’t sufficient any more.”

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