Lots of press attention has gathered around the latest research on prostate cancer screening. To be clear: there is no NHS screening programme for prostate cancer screening. Instead, if men want a screening PSA test they can ask for it from their GP.
The DoH’s press release in response to the latest research looks like this:
“A British Medical Journal study suggests that men should receive a prostate-specific antigen (PSA) level test at the age of 60. Research shows the test can accurately predict if a man has a high risk of prostate cancer, and target screening. A Department of Health spokesperson said: “The earlier a cancer is diagnosed, the greater the chance it can be treated successfully. The PSA test can help detect prostate cancer. The Chief Medical Officer informed every GP in England that the test should be available on the NHS to men who make an informed choice to take it.”
But is that really what the papers say? There are two, both in the BMJ. The first is a systematic review and meta analysis of all the available research on the subject. I favour these kinds of reviews because they take account of all the evidence, not just what suits your point of view. They conclude
“The existing evidence from randomised controlled trials does not support the routine use of screening for prostate cancer with prostate specific antigen with or without digital rectal examination” and they also note that the harms of screening were not adequately documented in the research they analysed.
The other paper is a case control study which looks at the outcomes after men had a PSA checked in earlier life. They found that a higher PSA was associated with a higher risk from death with prostate cancer. However they did not attempt to intervene in patients who had a high score. This means that we do not know if earlier treatment would lead to better outcomes – and this is the essence of screening science.
The editorial which comes with the research is written by a US urologist and notes that “the effects of screening on overall mortality and mortality from prostate cancer were unclear and variable in two large randomised trials” which were published in 2009 in the NEJM. He then talks about the difficulties of risk stratifcation and concludes :
“For now, clinicians are best advised to individualise their approach to PSA based screening. Young men at high risk of prostate cancer, such as those with a strong family history and higher baseline PSA concentrations, should be followed closely and could also be considered for “risk reduction” approaches …. Conversely, elderly men and those with a low risk of disease could be tested less often, if at all. Approaches such as these will hopefully make the next 20 years of PSA based screening better than the first 20”
The problem exists that we don’t even know that testing high risk groups only will make screening better – work is currently being done to attempt to screen women at high genetic risk of ovarian cancer, for example, and even there it isn’t clear that it’s a helpful thing to do. The research needs to be done to try and address this.
But my question is: what were the DoH reading when they produced that press release?