From Dance with Chance blog:
The recent publication of two large-scale studies of prostate screening in the US and Europe attracted our attention. After all, (a) this was something we wrote about in our book, and (b) we are – all three of us – men of a certain age.
In the US study, 38,343 men received annual PSA (Prostate Specific Antigen) blood tests while 38,350 men were assigned to a control group. After 7 years of follow-up, the incidence of prostate cancer death per 10,000 person-years was 2% in the screening group – that is 50 deaths. In the control group it was 1.7%, or 44 deaths. Not particularly significant then.
The European study involved some 180,000 men. This time, however, the screening group was billed as having a 20.7% improvement in the survival rate over the control group. This seems impressive and a good reason for continuing with PSA screening – in Europe at least.
So are European doctors better at screening than their US colleagues? Or is it just that numbers can be deceptive?
There were 214 deaths from prostate cancer in the screening group and 326 in the control group. This means 112 fewer deaths in the screening group, or a relative improvement over the screening group of 20.7% – found by dividing 112 by 540 (540 = 214 + 326).
In absolute terms, however, the improvement is much less impressive, since there were 72,890 subjects in the screening group and 89,353 in the control group. This means 7.1 fewer deaths in the screening group than in the control group, for every 10,000 people. If we consider that the study lasted some nine years, this is a tiny improvement of less than one person per year.