The evidence suggest the harms of population screening for prostate cancer outweigh the benefits, so why does it remain so popular? It’s a complex issue, particularly for GPs who are on the frontline on decision-making, says Kristen Pickles from the School of Public Health at the University of Sydney. Pickles led a recent study of 32 GPS across Australia to illuminate the issues from their perspective. She outlines the findings in the post below.
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Kristen Pickles writes:
Prostate-specific antigen (PSA) testing for prostate cancer in asymptomatic males is an emotive and widely debated issue in Australia (and internationally).
In this country, there is no organised prostate screening program and most guidelines recommend against population screening, yet PSA testing is very popular.
Independent reviews of the available evidence suggest the harms of population screening for prostate cancer outweigh the benefits. Overdiagnosis (the psychological, physical, financial costs of unnecessary diagnosis and treatment) is widely considered the most concerning potential harm of PSA testing. But overdiagnosis is a complex concept to understand and explain for GPs and the public, and estimates of its magnitude vary widely. Responsibility for guiding men’s decisions about whether or not to be screened for prostate cancer has largely been placed in the hands of individual physicians, who currently receive mixed messages about the advisability of testing.
We recently published our report on a study of how Australian GPs balance the dilemmas of PSA testing, with a focus on how GPs think about and manage overdiagnosis in their day-to-day practice. We interviewed 32 male and female, and urban and rural GPs across Australia to illuminate the issues from the GP’s perspective.
The GPs we spoke to overall felt uncertain or conflicted about the right thing to do about PSA testing of men without symptoms. For some GPs the uncertainty created considerable burden. Many GPs were thinking about the harms differently than academics or epidemiologists, giving considerable weight to concern about missing cancers. These GPs talked about the harms of underdiagnosing prostate cancers (missing the opportunity to intervene in potentially preventable deaths) as much as those of overdiagnosis: one GP described it as a ‘balancing act’ because they believed both potential harms were important and serious.
GP responses to this complex situation were focused on minimising the risk of harm to their patients. Their judgements about this were made in reference to their personal view on how underdiagnosis and overdiagnosis should be balanced. We identified four main approaches GPs used to navigate PSA testing decisions, each associated with different practices, rationales, and outcomes (refer to Table 2 in the published paper for a detailed explanation):
- Some GPs preferred to offer patients PSA testing to avoid underdiagnosis.
It was more important to them to find possible prostate cancers than to worry about the harms of overdiagnosis. These GPs engaged in active PSA testing and felt obligated as GPs to do so. They advised men to have the test, advocated the benefits of early detection, and told stories about patients whose lives they believed had been saved following testing and treatment. They felt the medico-legal risk of not offering testing was too great. - Some GPs were strongly oriented to avoiding overdiagnosis and so tried to test as little as possible to minimise the harms.
They were guided primarily by research evidence and guidelines. They emphasised the harms of PSA testing when advising their patients; however they described feeling challenged in practicing according to the evidence when it conflicted with what they had witnessed in practice. They were very aware of the potential for some cancers to be missed because of their preference not to test. - Some GPs did not have an apriori preference to avoid underdiagnosis or overdiagnosis, but instead tailored their practice according to the individual patient in front of them.
Their decisions and rules shifted according to what the individual patient wanted to do, as did the extent of their communication. For example, if a patient was perceived as having no interest in PSA testing then it would not be discussed, but if a patient wanted information, an in-depth discussion would take place. - Some GPs did not think about underdiagnosis or overdiagnosis in the context of PSA testing.
These GPs considered PSA testing just another form of routine screening. Neither under nor overdiagnosis were perceived as issues of particular concern.
For GPs on the frontline, decision-making about PSA testing is extremely difficult and complex. Understanding GPs’ reasoning in this way helps to explain why different GPs are making different testing decisions in similar cases. Our finding that GPs are practicing and communicating very differently (having worked out their own way of practicing) is an important one. Variation in practice has ethical implications, as men are potentially experiencing unequal access to information and consent to PSA testing according to their GPs’ orientation. Yet these GPs were not acting arbitrarily. Most were simply doing the best they could in an almost impossible situation.
The difficult position GPs are in should be recognised in future efforts to address the problem of prostate cancer overdiagnosis. The NHMRC has recently produced an authoritative summary of PSA testing benefits and harms for GPs to discuss with their patients. Our findings offer important guidance for the implementation of such recommendations for GPs in practice. It seems likely that NHMRC guidelines will need to be actively translated into practice for GPs, and that, given the significant diversity in GP perspectives, different translation strategies will be necessary depending on a GP’s customary approach to the problem.
We have also interviewed 29 GPs in the United Kingdom which has a different approach to PSA testing: emphasis is on information provision and minimal PSA testing. We will compare the two systems to determine what we can learn from one another. The next step of this research is to engage key stakeholders to develop a framework detailing we mightthink critically about the ethical issues of PSA testing and disseminate this draft for public input and discussion.
Kristen Pickles is a PhD Scholar, at the Centre for Values, Ethics and the Law in Medicine (VELiM) in the School of Public Health, Sydney Medical School, at the University of Sydney.
