David Cameron has joined the King as the latest public figure to disclose his diagnosis of prostate cancer. In an interview with the Times this week, the former British prime minister revealed that, after a prostate-specific antigen (PSA) test earlier this year, a biopsy and MRI scan gave him the diagnosis. He has said that he was successfully treated with focal therapy.

While poor media reporting on health issues is nothing new, the rhetoric on prostate cancer screening is persistently terrible and seems now incapable of correcting itself, particularly on the PSA blood test.

Prostate cancer is common — roughly one in eight men will get it in their lifetime — and a blood test is widely publicised as a quick and easy way to find it. It’s therefore often asked: why aren’t men being offered this on a large scale, and just getting the test to see if they have it? Media outlets then say men should ask for one, hinting, perhaps darkly, that more should be done by the NHS with regard to male health. The UK National Screening Committee is now being placed under immense pressure to recommend some kind of prostate cancer screening for those at highest risk of suffering from the condition.

Yet this increased screening could cause problems. There is a phenomenon known as the “popularity paradox”. The PSA blood test will find lots of “abnormalities” as it looks for levels of the PSA protein in blood samples, which could indicate the presence of prostate cancer. People who have been tested and have been told they have abnormalities tell others that they should test, and this happens ad infinitum. And so more get tested, and more abnormalities are found. And it seems that far, far more people who have abnormalities are found than those who die from the disease. Taken together, this makes it look as though the testing is working and that we are finding and potentially helping more people when, in fact, the test is really picking up many “abnormalities” which are not going to become harmful.

This is the problem with prostate cancer screening and the current campaigns for it. Outlets consistently publish stories about politicians and celebrities who have had the test, found abnormalities, and may have found cancer. And because it is not a routine offer made to men in the NHS, the recommendation is usually that they should be prepared to “fight” to have it done. But does this approach do men any favours?

Proponents of screening think they are doing a good thing — of course, people want to do something to help when feeling powerless over a disease that can be aggressive and difficult to treat. But given we know that prostate cancer, left alone, often does not affect male lifespans, we should be careful that we are not just putting up diagnosis rates without actually stopping men from dying of prostate cancer.

The risk is that low-risk men have PSA screening and — several scans, biopsies and treatments later — end up with lifelong complications from treatment they didn’t need, as the cancer may not have caused them any serious harm alongside the risk that the test still doesn’t perform well enough to stop aggressive cancers from causing deaths. NHS rules are, as I write, that men can make an informed choice to have the PSA test. A large trial, TRANSFORM, should hopefully work out whether the PSA test, plus MRI scans, can limit the harms and maximise the benefits in a way that might make it a reasonably good screening test. But we are not there yet and, in the meantime, men deserve to have good health information rather than misleading claims and hype.

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Margaret McCartney is a GP and broadcaster.

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