Enhanced breast cancer screening could help more women with dense breasts

Extra cancer screening scans could help find more breast cancers in women with dense breasts, according to some of our latest research. 

Around 10% of women have very dense breasts, which means they have more fibrous and glandular tissue and less fatty tissue than other women. 

Between the ages of 50 and 70, women with very dense breasts are up to four times more likely to develop breast cancer than women with low breast density. Their breast cancers are also harder to see in mammograms, the breast x-rays used to screen 50 to 70-year-olds for breast cancer. 

That lowers the chances that doctors can find these women’s cancers early, when treatment is most likely to be successful. 

Our BRAID trial tested three new screening techniques with the potential to reveal more signs of early-stage breast cancer in women with dense breasts. 

Over 9,000 women joined the trial, which was led and coordinated by researchers at the University of Cambridge and Addenbrooke’s Hospital in Cambridge. After mammograms showed than none of the women had signs of breast cancer, 6,000 participants also received one of the three new scans. These picked up 85 cancers that had previously been missed. 

The two most effective techniques identified by the trial are known as contrast enhanced mammography (CEM) and abbreviated magnetic resonance imaging (AB-MRI). CEM found an extra 19 breast cancers missed by standard x-rays per 1,000 women, while AB-MRI found an extra 17. 

Mammograms already detect an average of eight breast cancers for every 1,000 women with dense breasts. The results suggest adding using CEM or AB-MRI alongside mammograms could help screening detect three times more cancers in women with dense breasts than it does today

From spotting cancers to saving lives

BRAID is the first study to directly compare how effectively new screening methods can detect early-stage cancers in women with dense breasts. The results show that new screening technologies have the potential to improve how breast screening programmes are designed in future, but there’s still more we need to find out.

Cancers detected through screening aren’t always life-threatening, so it’s also important to make sure that adding new screening tests doesn’t result in people receiving unnecessary treatments.

The next step is to investigate whether using the additional scans as part of screening will help reduce the number of people dying from breast cancer.

If one or both of CEM or AB-MRI are shown to help improve breast cancer survival, the BRAID research team estimate that they could be used to help detect 3,500 more breast cancers every year in the UK.

The trial’s statistician, Professor Stephen Duffy from Queen Mary University, London, said: “The NHS Breast Screening Programme has made a huge difference to many lives. Thanks to these results we can see that the technology exists to make screening even better, particularly for the 10% of women with dense breast tissue.” 

Dense breast tissue and breast cancer screening

Breast density isn’t related to breast size or firmness. It depends on the mix of different types of breast tissue, which varies naturally between women and is usually only revealed when they go for a mammogram.  

Dense breast tissue is called ‘dense’ because of the way it appears in x-rays. While fatty tissue appears transparent, dense breast tissue and early-stage cancers both look white, which can make it hard for radiologists to tell them apart. 

The two most effective scan techniques tested in the BRAID trial are ‘contrast-enhanced scans’, which work by increasing the contrast between healthy breast tissue and possible tumours.  

During contrast enhanced scans, people are given a special injection that temporarily makes their blood vessels more visible. Tumours in the breast have a lot of blood vessels, so these methods make it easier to detect cancer even in women with dense breast tissue.