-->
For the boys, prostate cancer screening is another case in
point. Screening is easy (just a blood test - a PSA) but like all screening programs
it is plagued by overdiagnosis, and the harms from treatment for this condition
are also quite significant (high rates of incontinence and erectile dysfunction).
The difference between this and breast cancer screening is
that there is less general acceptance, and more criticism from official
bodies and major academic journals and popular
journals, and also from the guy who invented the PSA test in the first place (here).
The large scale randomised trials (the best evidence) on
this topic give conflicting results regarding the effectiveness, and again,
they concentrate on disease-specific mortality (which always makes screening
look better), rather than overall mortality.
For the best explanation of the relative risks and benefits
of PSA screening, read this
article from some excellent public health academics from Australia, who put
the risks and harms into numbers, to make it more digestible. They conclude:
“you have to screen 1408 men and
treat an additional 48 men to prevent one prostate cancer death over
9 years. In other words, only 1 of those 48 men is going to benefit
over the next 9 years; the other 47 … have undergone treatment for no
benefit within this period.”
One factor that is usually ignored is that the success rate from PSA-motivated treatment (1 in 48 or whatever) is never compared with the success rate that could be expected from giving prostatectomies to men selected in some other way or indeed to men in general. Because even if you gave prostatectomies to men in general you will reduce prostate cancer deaths simply because they don't have prostates anymore. This type of preventative strategy is generally not acceptable (even though it would save lives) so if the PSA-motivated prostatectomy strategy is no more successful then that shouldn't be acceptable either, even though it may save lives. Chris O'Neill
ReplyDeleteFascinating idea. I wonder if the success of PSA directed treatment would be better than a similar number of prostatectomies done at random. No one would do the study, but a great way of thinking about it. Thanks.
Delete