BCAC is delighted to see the Royal Australian and New Zealand College of Radiologists (RANZCR) recommend mandating of breast density reporting in both breast screening and diagnosis. The updated position statement notes that those with extremely high mammographic breast density (MBD) are at a 2.1-fold increased risk of breast cancer, and this is associated with higher rates of breast cancer death. 

Dense breasts have more fibrous and glandular tissue that appears light grey or white on a mammogram while less dense breasts have more fatty tissue that appears dark. Dense tissue reduces the sensitivity of mammograms by masking the presence of tumours that also appear white, leading to underdiagnosis of breast cancer in those at the highest risk of developing it.

RANZCR notes that while screening mammography is of proven benefit in detecting cancer regardless of MBD, the addition of supplemental imaging tools such as tomosynthesis, ultrasound, contrast enhanced mammography (CEM) and magnetic resonance imaging (MRI) may detect additional cancers in women with dense breasts.

BCAC’s Secretary Fay Sowerby is pleased and relieved to see this milestone reached by RANZCR. Fay has led our advocacy since 2012 to establish every woman’s right to be informed of their MBD and understand their associated breast cancer risk. MBD is clearly visible on mammograms and Fay has long argued that women must be given this information so they can manage their personal risk through appropriate vigilance and informed decision making on whether to have additional screening procedures. Some private breast screening clinics already report density but BreastScreen Aotearoa (BSA) has remained silent, potentially disadvantaging those who engage in our national breast screening programme.

In October 2023 Fay provided a comprehensive review of worldwide evidence and practice on MBD to BreastScreen Aotearoa, urging them to measure, record and report MBD with every screening mammogram.  
“It’s clearly important that women with dense breasts are informed that they are both at higher risk of developing breast cancer and are less likely to have it detected by mammogram” says Fay. “Decisions on additional screening options can then be made in discussions with healthcare providers. It’s heartbreaking that some women with dense breasts have had regular mammograms only to find they had a tumour growing behind dense breast tissue.”

The US-based National Comprehensive Cancer Network (NCCN) released updated screening guidelines for women aged 40 years and over in 2023. For those considered to be at average risk of breast cancer but with dense or heterogeneously dense breasts they recommend discussing supplemental screening options. They note that ultrasound can increase rates of detection but may increase recall and benign breast biopsies. For those considered at high risk they recommend annual MRI after shared decision-making. Other options include abbreviated MRI, tomosynthesis, CEM and molecular breast imaging.

The European Society of Breast Imaging (EUSOBI) published suggested guidelines in 2022 for women with high MBD, suggesting an aspirational goal of screening women aged 50–70 years old with extreme breast density with breast MRI every 2–4 years, in addition to mammography. RANZCR acknowledges that economic, human resources and accessibility may make adopting these recommendations difficult at this time but has committed to working towards a model of this gold standard with governments and regulatory agencies.

Fay comments “We celebrate the updated position statement from RANZCR and hope that it marks a decision point for BSA to report density with every mammogram, move towards implementing risk-based screening and ultimately to offer additional screening to those who need it.” 

Read our previous breast density articles on a woman’s right to know her MBD and why density matters.

For further details read our comprehensive submission to BSA.

For more discussion on breast density, view this Breast Cancer Foundation NZ webinar.

The updated RANZCR position statement can be read here.

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