• A new survey shows the urgent need for women to understand their breast density in order to pursue personalised and potentially life-saving screening options. (Universal Images Group Editorial/Getty Images)
Up to 50 per cent of women have dense breasts, and Asian women tend to have higher breast density.
Alyssa Braithwaite

26 Sep 2017 - 5:15 AM  UPDATED 26 Sep 2017 - 9:28 AM

More than two million Australian women have dense breasts, yet the majority of women don't know their breast density, and are unaware that having dense breasts means they can be five times more likely to develop breast cancer, according to a new survey.

Research by preventative health organisation Pink Hope reveals dangerously poor levels of awareness by Australian women of the risks that dense breasts pose for breast cancer, prompting calls for women to understand their breast density in order to pursue personalised screening options that could save their lives.

Dense breasts are made up of less fat and more connective/fibrous and glandular tissue.

Four out of five women (84.4 per cent) are unaware dense breasts increase the risk of breast cancer. Women with dense breasts are four to five times more likely to develop breast cancer. Furthermore, almost two thirds of women (65.8 per cent) have no idea breast density can obscure a lesion or lump on a mammogram.

Women with dense breasts are four to five times more likely to develop breast cancer.

Contrary to what many people believe, big breasts are not more likely to be dense. 

"You can't tell from the size or appearance of the breast, or the feel of the breast, you can really only tell from a mammogram," Professor Mary Theresa Rickard, AM, chief radiologist at Sydney Breast Clinic, tells SBS.

"We classify dense breasts as being more than 50 per cent of the area of the breast on the mammogram as [showing up as] white.

"But what we know if that if we compare the people who have a 10 per cent or less dense breast compared to people who have a 75 per cent or more dense breast, then the people in the 75+ per cent category have five times the risk of developing a breast cancer compared to those in the lowest category. So it's a big difference."

Breast density does change as you age. Between 40-50 per cent of women aged 40-74 have dense breasts. The figure is probably higher for women under the age of 40, but because people generally don't start having mammograms until the age of 40, there is no large population data for younger women.

Professor Rickard says some ethnicities are more likely to have dense breasts.

"We know that Asian women have higher breast density compared to Caucasian women," Professor Rickard says.

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"Asian countries generally speaking have a lower incidence of breast cancer than do western countries, but just the same, within their populations of Asian women there's quite a lot of variation. For example, studies in Malaysia would show that Chinese women have denser breasts than say the Indian women, who have denser breasts than say the Malays.

"And then you can see that that relates to incidences of breast cancer as well. So even though over-all that country would have a lower incidence than we do here, the Chinese would have the highest incidence in that country, because they also have the highest breast density in that country. Higher density means higher risk." 

Breast cancer runs in 28-year-old Sydney nurse Aimee Ho Sing's family.   

Her aunt died of breast cancer when she was just 27, while her mother had ovarian cancer. She was also BRCA positive (the gene made famous by Angela Jolie with can predispose women to breast and ovarian cancer), so from the age of 20 her doctors kept recommending she undergo a mammogram.

Ms Ho Sing says the clinic was reluctant to give her a mammogram, because she was so young. When she eventually convinced them she needed one, she found out she had dense breasts which made it very difficult to see any potential cancer.

They did pick up something but because her breasts were so dense they couldn't tell if it was fibroids, a fat deposit or a lump. Ms Ho Sing ended up having a biopsy which confirmed it was nothing to be concerned about.

But rather than face expensive and potentially ineffective screenings every six months, she opted to have a double mastectomy and reconstruction at the age of 23.

"This is another new thing that women can be aware of. You just need to be aware of your body," Ms Ho Sing says.

She recommends all women make themselves aware of their own breast density so that they can make informed decisions. 

"This is another new thing that women can be aware of. You just need to be aware of your body," Ms Ho Sing says.

"I started working in the breast cancer surgery and plastics reconstructive ward, and we see a lot of young people come through, in their early 20s and early 30s, who have breast cancer.

"I think this should be a big campaign that should definitely be pushed."

Breast density is recognised internationally as a risk-factor, and in the US and Europe a personalised approach to screening has been embraced.

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In the US much of the awareness has been driven by Connecticut woman Nancy M. Cappello, 59, who was not told that she had dense breast tissue until after doctors found an advanced cancer that mammograms had missed.

She set up the website, Are You Dense?, and has been credited with helping about half the states in the US pass legislation that says that women must be told their density and must be offered some information about what to do next.

Professor Rickard says Australia has been slow to act on breast density.

"In Australia the way to manage breast density has not yet been formally agreed to, and so our lack of public education and one-size-fits-all approach to screening with standard mammography only persists," she says.

"We need women to know this if they're to be their best breast advocate."

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