Participants in cancer screening are willing to accept some risk of wrong diagnosis, according to a new study.
A new survey has found that the public have a wide variety of opinions on over-diagnosis.
Researchers set out to establish how much over-diagnosis is acceptable to participants.
Dr Ann Van den Bruel of Oxford University, UK, and colleagues ran an online survey of 1,000 UK adults on screening for breast, prostate, and bowel cancer.
Participants were given details on annual rates, treatments and side-effects, and asked their opinion on screening that could prevent either a 10% or 50% drop in cancer-specific deaths. They then responded with the maximum number of people they thought could be over-detected and over-treated for each benefit.
Results were highly variable, say the team. Up to 7% would accept no over-detection at all, whereas up to 14% who would accept over-detection of the entire population. But overall, most respondents would accept 113 to 150 people over-detected by screening to avoid one person dying.
Invitations for screening should include clear information on the likelihood and consequences of over-detection to allow people to make an informed choice, the researchers say.
Also in the journal, Professor Alexandra Barratt of the University of Sydney, Australia, writes that clear figures on breast cancer over-diagnosis are urgently needed.
"It was thought that the benefits of early detection and treatment would outweigh any risks of treatment," she writes. "However, evidence of the unanticipated harms of mammography screening has fuelled debate about whether such screening should be changed or even abandoned."
Screening policy "should be based on demonstrated ability to achieve equivalent benefit to harm ratios and not on the assumption that increased detection will achieve a net benefit," she concludes.
Van den Bruel, A. et al. People’s willingness to accept overdetection in cancer screening: population survey. BMJ 4 March 2015 doi: 10.1136/bmj.h980 [abstract]
Barratt, A. Overdiagnosis in mammography screening: a 45 year journey from shadowy idea to acknowledged reality. BMJ 4 March 2015 doi: 10.1136/bmj.h867 [abstract]
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