Cancer screening, participant information and the scientific debate
Cancer screening programs which aim to detect cancer early and thereby save lives are widespread and increasing. Breast cancer screening with mammography is among the most common screening programs, carried out as national or regional screening programs in all western countries. The logic behind cancer screening is that early detection of pre-symptomatic cancer will give better prognosis for the individual patient, but the effect of a screening program can only be found at population level.
Evidence of the effect of mammography screening has been contested among scientists, due to flaws in the randomized controlled trials of mammography screening. Disagreement between scientists has led to disparities on which information women should have before joining a screening program, and how they should be included in such programs. Since women invited to breast cancer screening are free of symptoms, and thereby not a patient per se, questions have been raised about informed choice in breast cancer participation.
While some women who participate in screening are saved from breast cancer deaths, others may be subject to increased morbidity due to having a false positive mammogram screen or being overdiagnosed and treated for cancer that would have given no symptoms throughout the woman’s life span. However, overdiagnosis from screening is more of a statistical phenomenon than clinically detectable. This raises questions about its significance, as well as leads to questions about what women should know before making a choice about breast cancer screening participation.
Other issues on which scientists have differed is the psycho-social consequences of having a false positive screen, whether a program should be opt-in or opt-out – and which consequences such organizational structures may have on the social stratification of participation. Why are such debates carried out to various degrees in different countries? However, screening participants have other worries than those apparent in scientific debates. How and why are participants’ concerns about screening information different from the scientific debates? How could we understand these conflicting interests between different forms of knowledge?