The many unanswered questions related to the German skin cancer screening programme.

In 2008, the first nationwide skin cancer screening (SCS) programme in the world was established in Germany. The main reason to implement the SCS programme in Germany was the expected reduction of costs of care due to earlier detection of skin cancer. The aim of this commentary is to raise and discuss several unanswered questions related to the German SCS programme. The evidence of a temporary mortality decline of skin melanoma after SCS in Schleswig-Holstein is lower than previously assumed and the temporary decline may have been caused by other factors than screening (e.g. awareness effects, selection bias, data artifact, and random fluctuation). The evaluation of the nationwide effect of SCS on skin cancer mortality is hampered by birth cohort effects and low quality of the routine cause-of-death statistics. The nationwide skin melanoma mortality did not decrease from 2007 through 2014. The time interval between screenings after a screening without pathological findings is unclear. Appropriate research designs are needed that monitor and evaluate the effect of SCS not only on skin cancer mortality but also on other factors that may help to judge the potential benefits and harms of SCS including aggressiveness of therapy, costs of care, quality of life, and stage-specific incidence rates of skin cancer. Furthermore, SCS may profit from a high-risk strategy instead of population-wide screening and from newer technologies for early detection of skin cancer (e.g. dermoscopy).