It is hard to argue with the notion of early detection of disease. After all if disease is found early it is easier to treat and the outlook is better. Hence there has been a push for more and more screening tests to be done. Whereas much trialing is done on pharmaceuticals before they are released, the same does not apply with tests. So we find out much later if what is done actually helps!
The US Preventative Task Force has publicly said that prostate screening (with PSA blood testing) has no benefit. This has set the hares running, not surprisingly. Yet the evidence is stark. Over twenty years follow up there is no difference in mortality between men who are screened and those who are not.
It gets worse though as for every man who has “life saving” surgery some 48 will have needless surgery and a good percentage of them will wind up incontinent or impotent or both. This is aside from the huge number of men who have biopsies which do not benefit them and who can end up with bleeding, infections and hospital stays.
Whilst there is considerable appeal in the notion of getting a simple blood test to know if you have cancer, this is not the reality. The inventor of the test has described its use as a screening test as a “flip of a coin” and the widespread screening programs as a “public health disaster”.
The fact that a test can be done does not make it a useful test. Far from telling a man if he has cancer or not, the PSA gives a reading which tells you next to nothing. A “normal “ reading does not mean cancer may not be present. More importantly an “abnormal” reading does not mean cancer is present.
Furthermore in many men, cancer of the prostate is something they die with, NOT of. Some 80% of eighty-year-old men have prostate cancer found at autopsy. Even in 40 to 60 year old men this figure is as high as one third! In other words the presence of cancer cells is not a death sentence.
And here is the other failing of screening. Even when we detect cancer we do not know who has an aggressive form which may be life threatening and who does not. When you see people in the media (particularly celebrities) claiming a test saved their life there is a fair chance they would have lived anyway.
An analogy would be a lottery winner saying that, because they won first prize, that everyone should buy a ticket, and that they too will win.
Whilst it is likely that, in some cases testing may be life saving, the odds of that are 2% at best. There is a 98% or greater chance of treatment not extending life and a 30% chance of life being made worse due to complications of surgery.
It is hard to wrap our heads around the notion that finding early cancer is not good. That is the reality though. It reflects that cancer is not a linear progression through to death in all cases and shows that we understand less than we think we do. The other reality is that medicines ability to find things exceeds its ability to understand what it finds.
There will be howls of protest from medical and advocacy groups. Both have a vested interest as less “disease awareness” means less work for some doctors and less funding for some groups.
It would be great to have a useful screening test but we do not. The dilemma was well summed up by Dr Len Litchfield MD Deputy Chief Medical Officer, American Cancer Society who wrote;
“We have invested over 20 years of belief that PSA testing works. Catch it early, treat it early, and get it out. Save a life. That’s the mantra many of us–including me, as a practicing physician–believed. And here we are all of these years later, and we don’t know for sure. That is not an acceptable situation. Plain and simple, we have not done our homework to prove our point. And the chickens are coming home to roost.
Unfortunately, those “chickens” are men like me who dutifully get our blood tested every year. We have been poked and probed, we have been operated on by doctors and robots, we have been radiated with fancy machines, and we have spent literally billions of dollars. And what do we have? A mess of false hope?”
The decision to have a PSA test or not, must rest with the individual man. Armed with all the facts rather than just hype, an informed decision can be made.