LÃ¤kardagarna (physician days) in Orebro is an annual course arranged by the Orebro Society of Medicine in collaboration with The Swedish Society of Medicine. In the year 2000 the title was "Prevention and early diagnosis of cancer. What do we know? What do we believe? What do we do?" With general practitioners as the target audience, the course covered basic biological science, risk factors, screening, ethical questions and the general practitioner's dilemma. This article reviews four selected contributions: 1) What is cancer? 2) Possible importance of the fetal stage for later risk of cancer; 3) Infections as a cause of cancer; and 4) Screening for cancer.