The LORIS trial: addressing overtreatment of ductal carcinoma in situ

An unforeseen consequence of the introduction of mammographic breast screening has been the marked increase in the number of women diagnosed with ductal carcinoma in situ (DCIS) [1,2]. In 2009–2010, 2830 women were diagnosed with in situ carcinoma through the National Health Service Breast Screening Programme (NHSBSP) [3]. Screen-detected DCIS now accounts for 20% of ‘cancers’ identified through breast screening. However, the intent of breast screening programmes was to detect early invasive cancer, not to identify DCIS.