It is a 'hidden’ risk factor that can increase a woman’s chances of developing breast cancer six-fold. It cannot be seen, or felt. It has little relationship with breast size or weight. And it fluctuates throughout her life.
And, although doctors know all about it, and it affects up to half of all women, we are not routinely told about it.
Well, not in the UK.
As of this month, all women in the US having a mammogram – the type of X-ray used in breast cancer screening – will be informed about this specific risk: dense breasts. Breast density refers to the ratio of fat to glandular and connective tissue – the less fat, the denser the breast. The denser the breast, the greater the cancer risk.
The American initiative came after sustained campaigning from patients who insist it is vital in helping women understand the overall risk that they might develop breast cancer – a disease that hits one in eight. With the knowledge, women with dense breasts will be able to take steps known to reduce their risk, such as maintaining a healthy weight and limiting alcohol intake.
It may also mean they’re offered more regular or different types of scans, helping to catch cancer if it develops at the earliest stage, boosting survival chances.
In the UK, if a woman is found to have dense breasts during a mammogram, which are offered every three years between the ages of 50 and 70, it’s not even noted on her medical records
In the UK, however, if a woman is found to have dense breasts during a mammogram – offered every three years between the ages of 50 and 70 – it’s not even noted on her medical records.
Now, experts and campaigners in the UK are calling for an overhaul in screening protocols, as emerging research shows that breast density could be a more meaningful breast cancer predictor than family history.
They say hundreds of thousands of women are being left in the dark about their true breast cancer risk – and could be having tumours repeatedly missed during routine scans.
’Women need to be told about their breast density,’ said
former breast surgeon Dr Liz O’Riordan, who has had breast cancer three times.
’Evidence proves that women with dense breasts are more likely to get breast cancer. And in this case, knowledge is power.’
Countryfile presenter Julia Bradbury, 54, has spent the past four years advocating for dense breast awareness, alongside undergoing treatment for breast cancer. She first felt a lump in her left breast in early 2020, but it took a year and three 'clear’ mammograms before the tumour was discovered.
Countryfile presenter Julia Bradbury, 54, has spent the past four years advocating for dense breast awareness, alongside undergoing treatment for breast cancer
Breast tissue shows up as white on mammograms, as do tumours. It can be hard to differentiate the two in the X-rays – indeed, mammograms fail to show lumps in up to half of women with dense breasts, according to research.
Julia told the MoS of her 'disappointment’ in the health service’s failure to protect the thousands of women who, like her, have had their cancers repeatedly missed.
’At one of my mammograms I was told that I had dense breasts but it wasn’t a formal notification and it didn’t mean much to me,’ she explained.
’At first it sounds quite good, having dense breasts, doesn’t it? I didn’t understand the implications at all, the increased risk of cancer and the difficulty spotting cancer via a mammogram. If I had known these earlier, I would have been able to do more research and make an informed decision about what else I could do. I would have pushed further, asked for more scans and asked why my doctors weren’t concerned.’
Now, she hopes the UK will follow America in requiring doctors to tell women about their breast density.
’The more people know about themselves, the more they can plan accordingly,’ she said.
’And the earlier any cancer is diagnosed the better the treatment options and outcomes.
’Every time I do a story about this, hordes of people – women and men – message me saying they hadn’t even heard about dense breasts.’
More than 55,000 women in the UK are diagnosed with breast cancer every year. And while nine in ten survive, the disease still kills more than 11,000 every year.
’Dense breasts have nothing to do with how big your breasts are or how firm they feel, and the only way to know is by going for a mammogram,’ says Dr O’Riordan.
’They’re perfectly normal – in your teens, 20s and 30s, your breasts are naturally dense.
’Glandular tissue produces milk so it’s needed when a woman is fertile. But as you reach menopause and oestrogen levels drop, breasts naturally become less dense as that glandular tissue turns into fat.
’However, nearly half of all women over 40 still have dense breasts – and some women in their 70s and 80s do as well.’
Breast density is usually first picked up when a woman begins breast cancer screening. For those with moderately dense breasts – about 40 per cent of British women – the chances of developing cancer are believed to be double those of women with fatty breasts.
And for the 10 per cent of women in the densest category, research suggests the risk of cancer is six times greater.
’Dense breasts do not mean that you will get breast cancer – it just increases your risk,’ added Dr O’Riordan. 'Many studies show that over ten years, women with dense breasts are four to six times more likely to get breast cancer than someone with fatty breasts. The frustrating thing is that we don’t know why.’
Some theories link the high cellular content of dense breasts to a greater likelihood that abnormal cells will develop.Others think it could be due to higher levels of oestrogen, the female sex hormone that also drives many breast cancers.
Whatever the truth, campaigners say that by not informing women about their breast density – nor offering them MRI and ultrasound scans, which are better able to detect tumours than mammograms – thousands of cancers are being found far too late.
’It’s been well known for many years that women would benefit from better screening,’ explained British breast density campaigner Cheryl Cruwys, 58. 'Yet still, women come to me saying – 'If only I’d known’.
’In France, they automatically do supplementary screenings for women with dense breast tissue. In America, they now have to inform you of your relative risk. But in the UK, women are literally on their own.’ Ms Cruwys started campaigning – founding online resource Breast Density Info UK – after she was diagnosed with breast cancer in 2016, aged 50.
Living in France at the time, she arrived for her first routine mammogram without any concerns about her health. 'I didn’t have any risk factors as far as I knew and when I had my mammogram, it seemed to be clear,’ she said.
As of this month, all women in the US having a mammogram – the type of X-ray used in breast cancer screening – will be informed about the risk of dense breasts
But in France, as in Austria and a number of other European countries, the health system works differently. Women found to have dense breasts during a mammogram are immediately given further screening – usually an ultrasound.
’In my case, the ultrasound found something the mammogram didn’t – an 8mm tumour,’ Ms Cruwys said. Now in remission, she considers herself 'walking proof’ of the importance of early detection.
’We know categorically that if I had been in the UK when I had that first mammogram, my cancer would have been left undetected,’ she said.
For US campaigner JoAnn Pushkin, 64, it was this lack of transparency that spurred her to push for change in the country’s health policy. 'The campaign grew out of grassroots efforts of women who were all diagnosed with breast cancer at a later stage than necessary,’ she told The Mail on Sunday.
’We were never told that we had dense breasts, that it increases our chances of breast cancer, or that it drastically reduces the efficacy of our mammograms.
’So – without any family history of cancer – we went for our annual mammograms, dutifully did our self-exams, and yet our cancers were still missed year after year.
’I’d been going to annual screenings since the age of 40.
’When I finally felt a lump, aged 45, the technician told me it had likely been growing for three to five years. And in each state we campaigned in, there were women with horror stories much like mine. Breast density is the only one that a doctor has to tell us. We can’t find out by ourselves.
’And how is a woman supposed to participate in her own breast safety surveillance if she is never told about it?’
Women in the US are now informed of their breast density in a letter 30 days following their mammogram appointment, using the density scoring system known as BI-RADS. This has four categories of varying density.
As well as informing a woman of her category, healthcare providers are also required to suggest that those with particularly dense tissue seek further testing.
Yet in the UK, no such scoring system exists: the first time a woman’s breast density will be officially logged by the NHS is usually after she has been diagnosed with breast cancer.
Dr Fiona Gilbert, professor of radiology at the University of Cambridge and breast cancer expert, hopes that the UK’s breast cancer screening programme will be updated to better care for women with dense breast tissue within the next five years.
’The policymakers are very aware of this issue of breast density and have either commissioned work or are waiting on trial results to be able to move forward and implement some changes,’ she said.
In the US, where breast density is already accepted as a serious risk factor for breast cancer, celebrities have been speaking out about the importance of secondary screening for years.
Country star Sheryl Crow, 62, who was diagnosed with early stage breast cancer in 2006, has discussed her experience of discovering she had dense breast tissue extensively.
The All I Wanna Do singer, left, had been having annual mammograms since she was 35 because her dense breasts made self-exams difficult, and doctors caught her cancer early. Crow is now in remission.
Country star Sheryl Crow, 62, who was diagnosed with early stage breast cancer in 2006, had dense breast tissue and is now in remission
And television presenter Katie Couric, 67, has written about having dense breast tissue on her website – revealing that she gets a routine ultrasound alongside her yearly mammogram. It was during one of these scans that her doctor found an abnormality in her breast, leading to her being diagnosed with early stage breast cancer.
’Please get your annual mammogram,’ she advised readers in 2022. 'But just as importantly, please find out if you need additional screening.’
Pictured below is Julia Bradbury’s mammogram, which shows how her dense breast tissue originally hid her cancerous tumours.
In fatty breasts, a mammogram can easily identify cancer – which shows up as a white dot or smudge among largely transparent, or black, fatty tissue.
In an X-ray of a dense breast, however, the glandular and connective tissue also shows up as white – as seen in Julia’s mammogram.
The mammogram of Julia’s breast, with the dense tissue hiding her tumours
During the 12 months following her finding a lump in her left breast, Julia had three mammograms, all of which failed to pick up the tumour.
Although told she had dense breasts, she says the implications of that were not fully explained and if she had known she would have been more proactive about her care.
Julia says: 'I would have been able to do more research and make an informed decision about what else I could do. I would have pushed further, asked for more scans and asked why my doctors weren’t concerned.’
Julia is now in remission. Her bestselling book
Walk Yourself Happy – inspired by her health journey – is available in paperback this week.
