ABSTRACT
The National Health Service Breast Screening Programme (NHSBSP) was introduced in 1988, inviting all women aged between 50 and 70 years for mammographic screening. In 2021–2022, the screening programme in England screened 2.2 million women and identified 20,152 cancers (9.2 per 1,000 screened). 1 Breast screening is effective at reducing mortality by 20%–30% based on a number of randomised controlled trials (RCTs), the earliest being the Health Insurance Plan (HIP) study carried out in New York in 1963. 2 One of the largest, most notable and influential studies, prior to implementation of the NHSBSP, was the 1985 ‘Swedish Two-County Trial’. Its findings were key in a 1986 report to the health ministers of the UK recommending breast screening (the Forrest Report). 3 Conducted by the Swedish National Board of Health and Welfare, this trial randomised patients from the counties of Kopparberg (renamed Dalarna in 1997) and Östergötland. Initially published in 1985, it was criticised for presenting overall mortality which did not differentiate deaths from breast cancer from other illnesses, for not assessing mortality in separate age groups and for a lack of comparison between the two counties. The present paper was published several years after the original report, elaborates on the initial publication with additional follow-up and addresses some of the observed shortcomings.
