The research was first published last year, but has been re-examined following a series of protests from cancer organisations over the findings. Now one of the world's leading medical journals, The Lancet, agrees that there is not enough evidence from large-scale trials to support breast screening. However, cancer charities and the UK cancer screening programme disagree strongly with their verdict. All UK women aged between 50 and 64 are currently offered screening once every three years. The BBC's Daniel Sandford reports.