Women set to be told of higher cancer risk due to breast density at screening

Women with particularly dense breast tissue are twice as likely to develop breast cancer

Women screened for breast cancer are to be told if they have very dense breasts, under changes to the screening programme under consideration.

Although high breast density is a known risk factor for breast cancer, women undergoing screening through the BreastCheck programme are not provided with this information at present. It is likely that women in this category will then be offered diagnostic tests for breast cancer, once decisions have been made on how to categorise breast density and how often to test those affected.

Changes to current procedures are seen as inevitable in light of new advice from European bodies. Last month, the European Commission, in updated advice to member states, said they should consider MRIs for women with particularly dense breasts.

This follows a recommendation by the European Society of Breast Imaging (Eusobi) that all women be appropriately notified about their category of breast density.

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Pointing out that women with particularly dense tissue are about two times more likely to develop breast cancer than the average women, Eusobi recommended that women in this category should be offered a breast MRI.

“We have known for a long time that the performance of mammography screening in women with extremely dense breasts is not very good,” said its past president Fiona Gilbert. “However, we had nothing better to offer. Recent MRI screening trials [in the Netherlands] have largely changed this.”

Dense breast tissue has more cells that can become cancerous. It can also make a scan difficult to read, as any lumps or areas of abnormal tissue are harder to see.

In Ireland, the National Screening Advisory Committee, which makes decisions on changes to screening policy, is evaluating an application to report breast density in BreastCheck. It is also considering proposals to extend the programme to younger women, who are more likely to have dense breasts.

Dr Alan Smith, public health consultant with the National Screening Service (NSS), acknowledged the new European recommendations have set in motion further debate on the issue.

“I think it is inevitable the recommendations will be updated,” he told The Irish Times, “but then it’s a case of how they are implemented.”

Decisions will have to be made as to how to measure breast density, he said, whether “by eyeball”, categorisation by a clinician or by automated means. Grading categories will also have to be defined; in the US, for example, there are four. It will also have to be decided how often to refer women with dense breasts for an MRI, and how to communicate with women.

Scientists at the Royal College of Surgeons in Ireland are researching the relationship between breast density and breast cancer.

According to the NSS, there is a “low level of certainty” around the issue of breast density and “limited consensus” among healthcare professionals on the most appropriate approach for managing women with dense breasts. It identified these uncertainties as the appropriate measure for breast density, the method of measurement and what to do with those women identified as being at higher risk.

The Eusobi recommendation acknowledged that there are “clear downsides” to breast cancer screening, and called on radiologists to “inform women appropriately”.

Siobhán Freeney became a patient advocate after receiving a delayed diagnosis of breast cancer within six months of a clear mammogram. That was over six years ago.

“Much further down the road, I was to discover that my cancer was missed because of my dense breast tissue,” she said. “I had never been notified that I had ‘dense breasts’, or that my screening mammograms could not be reliably interpreted.”

“There is still no standard operating procedure within BreastCheck for notifying a woman when her mammogram shows she has dense breasts. If a woman isn’t told, she won’t know to ask about additional screening.”

Freeney set up beingdense.com to campaign for a change in screening practice. “Currently, women in Ireland are not routinely notified about their personal category of breast density,” she said.

“It is a mammographic finding, clearly visible on mammogram imaging, and known to be a more significant risk factor than familial risk. It can also mask cancers on mammograms, leading to delayed diagnoses and increased numbers of interval cancers.”

Paul Cullen

Paul Cullen

Paul Cullen is a former heath editor of The Irish Times.