LAUSR

The number of newly diagnosed cancer cases is increasing across Europe, much due to the increasing age of the population and exposure to risk factors such as obesity and smoking.1 At the same time, treatment options for cancer are expanding, but many of these new drugs are costly. There is concern surrounding how health care systems as well as patients will be able to manage increasing costs, and this economical discussion has largely focused on the expence of new cancer drugs.2 It has been estimated that 40% of cancer cases could be prevented if the current knowledge of the risk factors could be translated into effective primary prevention methods. Additionally, further reduction in cancer incidence and mortality could be accomplished through screening and other early detection methods.3 The benefits and importance of cancer screening programs has also been recognized by the European Union, which in 2003 issued its Council Recommendation on cancer screening,4 and in 2017 its report on the implementation of cancer screening in Europe.5 Currently, the European Union recommends screening for cervical, breast and colorectal cancers. So why is there still controversy regarding cancer screening programs? Cervical cancer screening was the first full-scale cancer screening program to be implemented in the Nordic countries. In Finland and Sweden, the screening programs reached national coverage by the end of the 1960s; Denmark and Norway started national programs during the 1990s. It has been estimated that during these 50 years of screening, over 60 000 cases of cervical cancer have been prevented in the Nordic countries.6 Due to the systematic approach of screening, cervical cancer has become a relatively rare disease in the Nordic countries. Much of the controversy around cancer screening has focused on screening for breast cancer with mammography. The main arguments against screening are the risks of overdiagnosis and the harms caused by treatment interventions for a non-clinical disease.7 Yet, as the authors Helvie and Bevers point out in their recent review,8 “the potential risk of overdiagnosis with screening must be balanced with the known harm over “overdying” without screening”. Why would we wait for a symptomatic occurrence of cancer, if it were possible to detect in a preclinical stage? In cancer, earlier diagnosis usually leads to better curative results, and less harmful interventions for cancer control, thus reducing the risks of treatment-related harms. Of the screening programs recommended by the EU, colorectal cancer screening has been the last to be implemented. The EU report5 shows that of the estimated 153 million women and men in the age group 50-74 years of age, 72% are already targeted by colorectal cancer screening in EU Member States which have adopted at least some policies to implement, pilot or plan for population-based screening programs. There is an increasing interest in implementing new cancer screening programs, in particular for prostate cancer9 and lung cancer.10 It is important to understand that there are many stakeholders who have an interest in screening, including scientists, funding bodies, patient organizations and commercial entrepreneurs. Sometimes, it is not easy to reach a shared understanding of the balance between benefits and harms, as the viewpoints of various stakeholders are somewhat different. If screening for cancer is used as means for cancer control, the key concern is not the black-and-white question of whether or not to screen. The key question is in the implementation of a cancer screening program. Firstly, there has to be evidence, that in this particular cancer, the benefits of the screening outweigh the harms caused by the screening. Secondly, screening is not only a test or a diagnostic method; the whole pathway from invitation to screening to treatment of the disease must be in place. The program should be accessible to all citizens allowing for true population coverage. Quality assurance and monitoring of the effects of the screening program cannot be neglected. It is only with these measures that the potential of cancer screening can be fully realized.