Is overdiagnosis emphasised in cancer screening decision aids?

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The risk of overdiagnosis is an important consideration when screening for cancer. Overdiagnosis is when a cancer is diagnosed that would otherwise have not led to symptoms or death, which can subject the patient to unnecessary treatment and potential harm. However, it must be weighed up appropriately with the benefits of cancer screening, therefore, it can be helpful to consult screening decision aids.

Researchers from PCHSS Research Stream 2.1, Thanya Pathirana, Professor Paul Glasziou and colleagues, present a comprehensive review of the available decision aids for prostate cancer screening that focuses specifically on overdiagnosis and shared decision making. Overdiagnosis occurs in 20% to 50% of screened prostate cancers, as it is common for prostate cancers to be slow-growing and not lead to harm for the patient. The authors of this review examined 41 publicly available decision aids which can be used as tools in deciding whether or not to undergo screening.

It was found that while the majority of decision aids included information on overdiagnosis, only 21% specifically used the word ‘overdiagnosis’. While this may present as a missed opportunity, this detail instead highlights the consideration of health literacy and accessibility of information, as individuals from diverse backgrounds may not understand what the term ‘overdiagnosis’ means.

As areas for improvement, Pathirana and colleagues emphasise the importance of communicating the risk of mortality between screening and not screening, as well as the prevalence of undiagnosed prostate cancer in the general population. By knowing how many men die of prostate cancer, or the prevalence of undetected cancer cells in men who have died from other causes, patients reading the decision aid may be better equipped to weigh up the pros and cons of undertaking prostate cancer screening.

The need for accessible and appropriate representation of health information underlies this review. Information and guidance regarding overdiagnosis and its costs and benefits can be best presented both in text and visually, to ensure that it is suitable for individuals with lower health literacy. As such, patient decision aids are an integral part of improving knowledge, supporting personal values, and helping patients make an informed decision on whether or not to undergo prostate cancer screening.

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