The Editorial in the 11 February 2004 issue of this Journal1 was written in response to my Viewpoint article in the same issue: Prostate cancer screening: is it possible to explain diametrically opposed views?2 The authors of the Editorial, David Lamb and Brett Delahunt, found some difficulty with the answer to this question, which was provided in the Viewpoint article. To summarise, it is possible to explain diametrically opposed views by weighting the benefits and risks of screening differently. Those who support prostate cancer screening assign great weight to the benefits of screening (despite the lack of evidence), and little weight to the risks. Those who do not support screening acknowledge the risks and recognise that, given the lack of evidence of benefit, these risks could outweigh any benefits of screening.

Recognition of these risks has led to caution even from previous supporters such as Professor Thomas Stamey, one of the initial advocates for PSA screening for prostate cancer in the 1980s, who wrote last year:

In their Editorial, Lamb and Delahunt argued that “absence of evidence is not evidence of absence.”1 This argument could be a valid argument for screening only if there were no harm associated with screening. Then, even if PSA screening turned out not to be beneficial, at least no men would have been harmed. Unfortunately we know that there is harm associated with screening, so if PSA screening turns out not to be beneficial, the net effect of screening will be to have caused harm to thousands of men. Even if it transpires that there is a benefit from screening, the harm must still be considered.

The point is, at the moment we do not know:

This information can only be obtained from the randomised controlled trials that are currently in progress.

Finally, and most importantly, Lamb and Delahunt suggested that I regard “self-requested screening” as unethical. In fact, my Viewpoint article did not address self-requested screening at all, but discussed the ethical implications of offering prostate cancer screening to men. I addressed this issue specifically because many readers of this Journal are health professionals who need to decide whether to offer PSA screening to their patients. This issue is not confined to population screening, since screening can also be offered opportunistically. It is the offer of prostate cancer screening that I believe to be unethical, because we do not know whether the harms of screening outweigh the benefits.

It would not (and should not) occur to most men that their doctor would offer them an unproven and possibly harmful screening test. Thus, men are likely to regard an offer of prostate cancer screening from a doctor as a recommendation to be screened, or at the very least an endorsement of screening. That is why I believe it is inappropriate for doctors to offer prostate cancer screening at present, especially because, as doctors, we should “first do no harm”. The Editorial by Lamb and Delahunt, in focusing on self-requested screening, addressed a completely different issue.

The difference between offering screening and responding to a request for screening was recognised by the National Health Committee (which also recommended against offering screening), in its recommendation: