Quality assurance in lung cancer screening.

The effectiveness of screening programmes is critically dependent on the accuracy of the screening test. Where this relies on clinical expertise, there is an imperative to assure that the level of expertise meets expected standards. In cancer screening involving images, the focus is on the reader. Auditing of results is fraught with difficulty because of the time taken to accumulate enough data with confirmed outcomes to identify underperformance before any harm is done. Late recognition can lead to the need for reanalysis and recall of screening participants with loss of confidence in the programme. External quality assurance (EQA) is a method that enables clinical expertise to be tested rapidly by using test datasets with confirmed clinical outcome. In the UK, the breast cancer screening programme has had EQA in place for over 30 years. This article describes the development of the first EQA process in lung cancer screening, using the experience gained from running the breast cancer EQA, and the proposed future developments.