Abstract
Screening for cancer is intuitively attractive. Well-run cancer screening programmes can save lives, reduce morbidity, provide reassurance to individuals about their health and encourage a focus on prevention and early detection. Despite the intuitive appeal, the harmful effects of screening (both potential and actual) are well documented. Harm to an individual includes over-diagnosis and treatment of questionable abnormalities, anxiety for those with false positive results and false reassurance for those with false negative results. One of the important, but often not well articulated, harmful effects at a population level is the potential for cancer screening to increase health inequalities between population groups.