Do we know the effects of colorectal cancer screening? A short communication on selective uptake and differential effects of colorectal cancer screening in Scandinavia.

Colorectal cancer (CRC) contributes extensively to the overall cancer burden, with substantial and increasing social inequality in both incidence and survival. In several countries, this social inequality in incidence and survival has been increasing over time, and the increase is expected to continue. To overcome this, it is advised to implement nationwide CRC screening programmes, as these are effective in detecting possible signs of CRC, hence identifying earlier-stage cancer and reducing mortality. However, little is known about the distribution of these effects across population groups. It is possible that the outcomes of CRC screening are not equally distributed among participants, but rather that the screening programme serves some population groups better than others. The aim of this short communication based on published data is to describe the status of selective uptake according to sociodemographic and economic factors in CRC screening in Scandinavia. Furthermore, we raise questions that need to be addressed in future research in order to grasp the full effects of the screening programme and ultimately to ensure high uptake as well as participation in subsequent diagnostic procedures across population groups.