Organized cancer screening programmes must be re-evaluated continuously 22.12.2014 Press release 22 December 2014 Organized cancer screening has been ongoing in Finland since the late 1960s. From early 1990s the responsibility was decentralized to municipal level as screening was considered to be a task for primary health care. Finnish social welfare and health care reform and reorganization of municipal responsibilities will cause changes in the coordination of the organized cancer screening in the near future. When to start new screening programmes In Finland, national population based cancer screening is in place for cervical cancer (ages 30-60, every 5 years) and breast cancer (ages 50-69, every 2 years). In addition, colorectal cancer screening was launched as a population based implementation programme in 2004 among volunteering municipalities. Only half of the target population (60-69 year old men and women) were invited and the other half will serve as controls. New screening technologies are constantly offered. But before an organized programme can be introduced, the information on benefits and harms need to be available. There are various harms from screening at population level which may counterbalance the benefits. An example is prostate cancer screening; in spite of a 20% mortality reduction observed in the ERSPC trial, the potential harm of overdiagnosis and late effects after active treatment have so far prevented the national screening to be initiated. Another potential new programme is lung cancer screening with low dose computed tomography (CT). Also this screening has proven beneficial in terms of mortality reduction in heavy smokers but the harms are due to many other false positive findings needing diagnostics and surveillance. Research is ongoing on e.g. stomach and ovarian cancer screening but so far the results are inconclusive and contradictory. In Finland, the well-established national programmes for cervical and breast cancer screening need continuous follow-up and evaluation. New tests and methods will emerge. Also other changes in the programme, e.g. age range for screening, should be well planned and evaluated. In Nordic countries we have large national registers on health and socioeconomic variables and biological samples along with data provided by the population in terms of surveys and queries. In the future, the use of all the available information will bring new potential to guide the use of resource and to promote public health.