The study, published today in The Lancet Digital Health, analysed anonymised data from 11.6 million women aged 20-90 from 2000 to 2020. All of these women had no prior history of breast cancer, or the precancerous condition called ‘ductal carcinoma in situ’, or DCIS.
Breast cancer screening is vital but has challenges. While it reduces breast cancer deaths, it sometimes detects tumours that are not harmful (‘overdiagnosis’), which leads to unnecessary treatments. This not only harms some women, but also causes unnecessary costs to the NHS. For every 10,000 UK women aged 50 years invited to breast screening for the next 20 years, 43 breast cancer deaths are prevented by screening, but 129 women will be ‘overdiagnosed’.
‘Risk-based screening’ aims to personalise screening based on an individual’s risk, to maximise the benefits and minimise the downsides of such screening. Tailoring screening programmes on the basis of individual risks was recently highlighted as an avenue for further improvement in screening strategy by Prof Chris Whitty. Currently, in risk-based breast screening, most models of risk work by estimating a woman’s risk of a breast cancer diagnosis. However, not all breast cancers are fatal, and we know that the risk of being diagnosed doesn’t always align well with the risk of dying from breast cancer once diagnosed.
The new model developed by the team works to predict a woman’s 10-year combined risk of developing and then dying from breast cancer. Identifying women at the highest risk of deadly cancers could improve screening. These women could be invited to start screening earlier, be invited for more frequent screenings, or be screened with different types of imaging. Such a personalised approach could further lower breast cancer deaths while avoiding unnecessary screening for lower-risk women. Women at higher risk for developing a deadly cancer could also be considered for treatments that try to prevent breast cancers developing.