Dense breasts can render mammograms ineffective at detecting cancer. Are you at risk?

The experience of a woman whose breast cancer diagnosis was delayed has highlighted concerns about information provided through mammograms. Krysty Sullivan had a regular mammogram in 2019 after experiencing breast and back pain. She was reassured when her mammogram did not detect any cancer.

But what Ms Sullivan did not know was that she had what are known as ‘dense’ breasts. Breasts are a combination of fatty and fibrous tissue, with dense breasts having a higher proportion of the latter.

A higher proportion of fibrous tissue is not a problem intrinsically, but can present potential issues during a mammography. Dense tissue and breast cancer both appear white on a mammogram. This makes it more difficult to detect breast cancers in dense breasts.

Despite that potential difficulty, diagnosis of a tumour is still possible. Breasts flagged as dense can be scanned via ultrasound, which can detect tumours not found in a mammogram.

It was through ultrasound that Ms Sullivan did find out she had two two-centimetre tumours. Disturbingly, though, that detection came almost a full year after the initial mammogram returned an ‘all clear’ result.

So what went wrong?

When to use a mammogram, and when not to use one

For Ms Sullivan, the first stumble came right at the start. She attended a local BreastScreen centre in Sydney, unaware that service was intended only for women without symptoms. Having subsequently learnt this and found a lump in her breast, Ms Sullivan attended a private clinic.

At that appointment, she was advised her breasts were too dense for a mammogram to be effective. An ultrasound followed, and Ms Sullivan’s tumours were found.

Until that appointment, Ms Sullivan was not aware of the issues that dense breast tissue could cause, or indeed that she had dense breasts. “I trusted that the first report had said ‘no cancer detected’,” she said. “I didn’t think that meant they couldn’t see anything.”

Startingly, Ms Sullivan may not have had a delayed diagnosis had she had her initial mammogram in Adelaide or Perth.

Why does location make a difference?

Ms Sullivan’s plight highlights what can happen when policies vary between states. In both Western Australia and South Australia BreastScreen services advise women with dense breasts of the reduced sensitivity of a mammogram. In other states, they do not.

Similar cases to Ms Sullivan’s have led to a clarification from the Royal Australian and New Zealand College of Radiologists (RANZCR), Last week, the RANZCR released a revised position statement. The statement recommends mandating the reporting of mammographic breast density (MBD) in both the screening and diagnostic settings.

The statement acknowledges varying incidences of MBD categories and associated risks. These include “increased breast cancer risk, mortality, and reduced mammography sensitivity in extremely dense breasts”.

The RANZCR also endorsed expanded use of tools beyond ‘standard’ mammograms to improve diagnoses. “RANZCR supports the consideration of supplemental imaging tools, such as ultrasound, tomosynthesis, contrast enhanced mammography and MRI, for women with dense breasts.”

Ms Sullivan underwent 16 rounds of chemotherapy and two surgeries. The changes should, however, improve the chances of an earlier diagnosis for future patients.

This would a welcome change to what Ms Sullivan is concerned is a system that divides rich and poor. “I worry we have a two-tier system, where some people are going into private clinics … but the masses aren’t.”

A full updated position statement is available here.

Were you aware that some breasts are too dense for a mammogram? Will you be seeking more information when you have your next screening? Let us know via the comments section below.

Also read: Everything you need to know about male breast cancer

Written by Andrew Gigacz

Andrew has developed knowledge of the retirement landscape, including retirement income and government entitlements, as well as issues affecting older Australians moving into or living in retirement. He's an accomplished writer with a passion for health and human stories.

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