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Patient Outcomes from Second film-readers and Test threshold relaxation in Breast screening: Observational evaluation (POSTBOx)

postboxWe have been screening women for breast cancer in England since 1988. This involves offering women mammograms (x-rays) of their breasts which NHS experts examine to spot signs of cancer. The aim is to detect cancer earlier when it is more treatable. A review of breast screening in the UK in 2012 led by Sir Michael Marmot concluded that breast cancer screening saves lives, but also causes harm through overdiagnosis and false positive results.

Overdiagnosis is where women have cancer detected at screening and treated, but it actually would never have given her any symptoms during her lifetime, so she is harmed by unnecessary treatment. False positive results is when a woman’s mammograms look like she might have cancer, but when she comes for more tests it turns out she doesn’t have cancer, and attending those extra tests can be very worrying. This study aims to use data already collected in the English NHS to investigate how to optimise breast cancer screening so that it provides more benefit (more lives saved) and less harm (less overdiagnosis, and fewer false positive results).

The study is led by Dr Sian Taylor-Phillips. She is working with Public Health England to bring together data for over 10 million women screened in the English NHS Breast Screening Programme, with records about whether they developed breast cancer, and what happened to them. They will look at differences in how the women were screened, and see if there are any patterns suggesting that some ways of doing screening are better than others. For example, she will be investigating whether we should be recalling more women for further tests after mammography, or fewer, and how many experts should look at each woman’s mammograms.

The study is funded by the National Institute for Health Research, and has ethical approvals from the NHS and approvals from the Office for data release. The results will be published in peer review journals, and sent to every screening centre who provides data.

Contact: Dr Sian Taylor-Phillips (


The short protocol for POSTBOx can be dowloaded here.