Breast cancer screening has been very effective in Australia, with five-year survival rates improving from 74% in 1991 to 94% in 2020, according to AIHW. However, we now know way more about which groups of women are more likely to develop breast cancer—and have more sensitive tests for detecting it.

This has led some experts to call for a new breast cancer screening approach that accounts for factors other than age, such as breast density and family history. Known as risk-adjusted screening, this could be several years away because we need trials to explore the benefits, risks and costs of different screening strategies.

In the interim, there are steps GPs can take to do the best for women at risk of breast cancer.

Why do we need a risk-adjusted approach?

Risk-adjusted screening is the most promising way to achieve a substantial improvement in breast cancer outcomes, says specialist breast surgeon Professor Bruce Mann, Director of Breast Cancer Services at the Royal Melbourne and Royal Women’s Hospitals and joint chair of the expert advisory group for the Cancer Council Australia’s Roadmap for Optimising Screening in Australia (ROSA) project—which has developed an evidence-based pathway towards risk-adjusted breast cancer screening in Australia.

“We know that finding cancer at an earlier stage—0, 1, 2a—is associated with very high survival, and less treatment is needed than when cancers are diagnosed at stage 2b, 3 or 4,” he says. “And the way that we’re going to find more cancers early is through better screening.”

This may involve screening some women from a younger age or more often, or using more sensitive tests such as breast tomosynthesis, MRI or contrast-enhanced mammography—all of which come at a cost.

Nor does everyone need it. Professor Mann stresses that our current approach is “very good for the majority of the population.”

So, which risk factors signal that a woman might need more than standard screening?

Dense breasts

Mammographic density is an important factor in assessing individual risk, Professor Mann says, noting women with denser breasts (BIRADS C or D) are more likely to develop breast cancer—and their cancers are more difficult to detect on standard mammograms.

Family history

Women are at higher risk if a relative (mother, sister, grandmother or aunt) has had breast or ovarian cancer—especially if multiple relatives were affected or the cancer developed at a younger age.

Genes

Around ten genes are known to be associated with breast or ovarian cancer, and women carrying these genes may be at very high risk, depending on which gene is mutated, Professor Mann says. “It’s a small proportion of the population, 1% or less, but a very important group.”

Research has also discovered patterns of subtle changes across the whole genome, known as single nucleotide polymorphisms (SNPs), that are associated with increased breast cancer risk.

“That probably explains a number of families where there’s no specific gene but there are a lot more cancers than would be expected by chance,” Professor Mann says.

History of breast cancer

Breast surgeon Dr Melissa Bochner, Head of the Breast and Endocrine Unit at Royal Adelaide Hospital, notes women with a past history of breast cancer fall into a higher risk group for which we need “a better and more evidence-based protocol.”

Currently, these women are advised to have a yearly mammogram indefinitely. However, this may not always be appropriate if, for example, the woman is older and more likely to die from something other than breast cancer.

What can GPs do?

While there are no evidence-based guidelines for dealing with these risk factors yet, GPs can follow some general principles to help women achieve the best outcomes.

Do a holistic risk assessment

Numerous factors impact a woman’s breast cancer risk, including things like alcohol consumption, weight, physical activity and parity—so it’s important to consider the full picture.

Professor Mann says women can use the iPrevent risk assessment tool to get 10-year and lifetime breast cancer risk figures.

Dr Bochner recommends CanRisk – a free risk assessment tool for health professionals. You need to create an account to use it. The Tyrer-Cuzick Risk Assessment Calculator is another option, but you need to buy a licence to use it clinically.

Deal with density

Professor Mann says that whatever a woman’s breast density, regular screening mammograms are key to breast cancer prevention. “This is the most important thing because even with high density, a mammogram is a good test and will find most cancers,” he stresses.

If the woman has no other risk factors apart from dense breasts, you do not necessarily need to do anything else. “Her risk of breast cancer is really very low and there is no automatic need for further tests. It’s very reasonable to just advise the woman to be breast aware, report any changes, make sure she does comply with screening.”

Organise adjunctive screening

Professor Mann says adjunctive screening is worth considering in women with dense breasts plus another risk factor.

“If someone’s got high density and it turns out her mum had cancer, and she maybe didn’t have children, or she’s on hormone replacement, then that leads me to recommend some further investigation,” he says.

“First degree family history is the one that worries me most and it usually worries the individual too. And that’s the situation where some form of adjunctive screening is often the right thing for the patient. And I would generally recommend contrast imaging.”

Women typically have to pay for additional investigations, which Dr Bochner notes contributes to health inequality and increases the risk of overdiagnosis.

However women who meet specific eligibility criteria qualify for Medicare-rebated MRI screening, provided they have a referral from a specialist.

Unless they carry a breast cancer gene, the referring doctor must run a risk assessment tool (such as one of those listed above) “which involves taking a complex personal and family history and putting a lot of data in,” Dr Bochner says. So it takes quite a long time to do that assessment.”

Which test is best?

There’s no definitive answer, and each adjunctive imaging modality has pros and cons.

What about genetic testing?

Genetic testing and counselling may be advised in women with a strong family history or who develop breast cancer at a young age.

Testing is Medicare-rebated under specific circumstances, usually in women diagnosed with breast cancer at a young age or with certain tumour characteristics, or who have a strong family history in addition to a personal history, Dr Bochner says.

While women can also buy these tests online for about $400-$500, Professor Mann says they are best ordered by a specialist who can interpret and discuss the results.

When to refer to a specialist

Women carrying one of the known gene mutations should be managed through a specialist clinic, Professor Mann says.

Dr Bochner suggests referring anyone with multiple risk factors, noting you can also refer anyone you are concerned about — including women with dense breasts.

Key takeaways:

• Encourage all eligible women to take part in BreastScreen.
• Consider the full picture, including factors like weight, parity, alcohol use and exercise.
• High breast density alone may not warrant any further investigation.
• In women with dense breasts and another risk factor (especially relevant family history), you may want to consider adjunctive screening.
• Some women qualify for MRI screening, but this must be ordered by a specialist to attract a Medicare rebate.
• Refer women with known gene mutations, multiple risk factors, or if you have concerns.