Objectives Cancer overdiagnosis is a polarizing topic, with much disagreement on its drivers, magnitude, and implications. Overdiagnosis is also complex, as various factors interact to influence said drivers, magnitude, and implications in different ways, exacerbating controversy on the topic. The objective of this presentation is to summarize the state of recent evidence on cancer overdiagnosis, focusing on the evolution of themes, objectives, and opinions published on overdiagnosis. We also provide a schematic illustrating how overdiagnosis literature has sought to influence nodes within the healthcare ecosystem within which cancer overdiagnosis occurs.
Methods We performed an exploratory review of literature on overdiagnosis published since 2000. An electronic literature search of MEDLINE and Embase was performed, using controlled vocabulary and keyword searching for the following terms: ‘neoplasm’, ‘cancer’, ‘tumor’, overdiagnosis’, overdetection’. Titles, abstracts, and/or full texts were screened for eligibility. Articles were included if overdiagnosis was a key focus of the publication and excluded if they focused on non-oncology therapeutic areas. Included articles were reviewed to extract citation data and key themes of the publication.
Results The search returned 2,801 articles, of which 387 were included. Almost half discussed overdiagnosis in the context of breast cancer (46%), followed by prostate (14%), lung (12%), thyroid (11%), and other cancers (5%); some publications focused on multiple specific cancer types. Thirteen percent covered overdiagnosis more generally (i.e., not within the context of a specific cancer.) Articles that were applicable to a specific setting were typically from Europe or North America, with very few from low- to middle-income countries. The number of articles published annually increased gradually from 2000, peaking in 2014, then decreasing and plateauing. Over this time, research objectives evolved. Prior to 2010, most publications aimed to describe the epidemiology of overdiagnosis; more recently, research shifted to focus on qualitative aims, such as gauging understanding, attitudes, and personal experiences with overdiagnosis. Sharing opinions on overdiagnosis has been a consistent primary focus of overdiagnosis publications, and the literature has also evolved in this respect. The number of authors that accept overdiagnosis exists, if not advocate for change in response, has increased over time, while the number of authors rejecting the existence of the problem, or the need for any response, has declined. However, this pattern differs by cancer type. For prostate and thyroid cancer there is general agreement on overdiagnosis, with over 90% at least acknowledging the problem, and 10% or fewer diminishing it. In comparison, greater disagreement exists for breast and lung cancer, for which roughly 27% of authors reject the existence of overdiagnosis, or strongly recommend against change in response to it.
Conclusions Literature on cancer overdiagnosis has evolved to discuss overdiagnosis as more than just a statistic, though progress towards less controversial discourse has not necessarily been achieved for all cancers. This presentation will describe how the objectives of cancer overdiagnosis research have evolved over the past 20 years, as well as opinions on cancer overdiagnosis, and how research efforts and published opinions have influenced change in care and overdiagnosis outcomes.
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