Introduction Citizens generally trust screening programs organised by their local health authorities. The same applies to screening tests carried out on an individual basis by their own doctor. This places a great responsibility on health authorities and individual doctors not only to carefully weigh the harms and benefits of screening but also to provide adequate information. Not only should they properly consider overdiagnosis as one of the main disadvantages of screening, but they should also communicate this risk to the public or their patients. However, this implies that doctors themselves must be aware of the problem of overdiagnosis, which is not self-evident. A review of the existing literature shows limited and at the same time conflicting results on this.

Objectives The primary research question is whether doctors are aware of the risk of overdiagnosis, their attitude towards it, and their willingness to inform their patients or the public about it. A secondary objective is to explore what factors and circumstances the participants believe to have shaped their current position on cancer screening, and the significance of overdiagnosis in this.

Method We conducted semi-structured interviews with a cross-sectional sample of physicians and healthcare professionals responsible for organising screening programs In Flanders (Belgium). Our research focuses on breast, prostate, and lung cancer screening. We combined random sampling with purposive sampling to obtain a multitude of perspectives. Recruiting will stop once data saturation has been reached. All interviews are audiotaped, transcribed verbatim, and analysed using the methodology of Thematic Analysis.

Results Data are still being collected and initial results will be presented at the conference. Preliminary analyses show that overdiagnosis is not at the forefront when doctors consider the potential disadvantages of screening. Other disadvantages which are more tangible, such as false positives, fear, pain, and financial consequences seem more relevant to them.

Conclusion This research will bring insight into what doctors know and think about overdiagnosis and their willingness to inform the public about it or discuss it with their patients.