Mammogram scans may be unable to detect “hidden” tumours due to high breast density present in thousands of UK women of breast screening age. The high-density tissue itself is also a cancer-risk.
Research by the charity Breast Cancer Campaign (BCC) found that more information about breast density could help identify women in more accurate risk groups. The organisation also announced £1 million will be invested in preventative therapy and studying of density.
“Risk Determination and Prevention of Breast Cancer”, published in the journal Breast Cancer Research today, said work would be needed to reverse the increase in breast cancer expected in the next decade. The charity said they needed to reach a “tipping point” when more cancers will be prevented in the general population, not just women at high risk.
Baroness Delyth Morgan, chief executive at BCC, said: “The best weapon in overcoming breast cancer is the ability to stop the disease occurring in the first place. We need better ways to identify who is most at risk.
“The emerging evidence on risk factors such as breast density, which we now know is putting hundreds of thousands of women at risk of breast cancer, must be taken into consideration and more must be done.”
High breast density is when there is more collagen and glandular tissue compared with fat, as estimated on mammograms.
Women with the highest density are up to five times more likely to develop breast cancer than women with low density, and twice as likely compared to women with average breast density. The cause of this link has yet to be found, though research has found a connection between high calorie diets and density later in life. The number of UK people diagnosed with breast cancer is expected to rise until 2030 due to a number of risk factors. The report identifies four key risks and prevention gaps, as well as lifestyle and biology.
There was a need to more accurately estimate risk in the general population and in women, including information about breast density. New preventative therapies were needed, said the study, and healthier lifestyles needed to be identified for women, particularly in relation to weight control, alcohol and physical activity.
It added there was a need for more understanding of the biology behind breast cancer risk, such as early first pregnancies and restricting energy intake.
Lead author Professor Anthony Howell, director of research at Genesis Breast Cancer Prevention at the University Hospital of South Manchester, said: “With current breast cancer risk models we know we can predict fairly accurately that 10 per cent of women in the population are at high or moderate risk of the disease. We also know that using currently available drugs, up to half of breast cancers can be prevented in these women.
“However, there is a major gap in how we identify women at high risk who could benefit from preventive therapy. Additionally, there is a gap in determining how much the risk assessment would be improved by adding additional information about other risk factors, such as breast density, and gene tests.”
James Jopling, director for Scotland at Breakthrough Breast Cancer, said: “Through detailed analysis of lifestyle and environmental factors, we are confident we can unravel some of the biggest questions about how to prevent the disease altogether.”