The problem with early detection of disease in medicine

Medicine is presented as being highly scientific. This is until information comes out which questions certain assumptions that underpin the practice of medicine.

One of the mantras of modern medicine is that early detection is good. This seems logical enough.

However there is an underlying assumption. That is that there will be a worsening of the condition if it is not detected and that treatment will improve the situation. What would happen if this were not the case? People would have treatment that they did not need and at best would not be better for it and at worst may suffer complications of the treatment.

Surely that is not the case you might be thinking. We have clinical trials and research to guide us. Unfortunately it is the case far more often than we think.

The best (or worst) example is with prostate testing. Last year the inventor of the PSA test wrote in the New York Times that when it comes to screening for prostate cancer the test was like flipping a coin.  There are also studies, which have concluded that for every one man, whose life is “saved” by screening, some 48 men have unnecessary surgery and many suffer impotence and incontinence as a result of this surgery. These men live no longer and their quality of life is impaired.

All this occurs because as soon as a raised PSA is found it will be acted on. Hence the case against screening and hence not “finding” levels to act on. It is important to note that screening involves testing people with no symptoms and no indication of disease. This is separate from investigating people with symptoms.

More evidence has now emerged. A study of 20,000 men aged 55 to 74 over an 11-year period showed that there was no benefit in annual screening. Some 80% of these men had an initial reading of less than three. After 11 years only 1% developed aggressive cancer and only 23 (0.15%) had died.

Doing a test once every eight years would see a reduction of 50% in the number of biopsies done. It would also reduce the number of prostate surgeries done needlessly although this number was not quantified.

A 20 year trial of 9,000 men published in the BMJ showed no difference in death rates in men who had regular screening compared to those who did not. The study concluded that the risk of over detection and overtreatment in screening is considerable.

The man who has his life “saved” will tell everyone. The man whose quality of life is reduced by needless surgery will not and (perhaps just as well) may not even know his fate.

There are other examples of how over diagnosing exposes many people to needless treatment. A new book has been published on this topic called, Overdiagnosed: Making People Sick in the Pursuit of Health.

Around 1,600 mammograms need to be done to find one breast cancer that would not otherwise have been found. For women aged 40-49 some 19,000 mammograms will have to be done and 650 women undergo unnecessary surgery and biopsies for the same one cancer to be picked up.

In skin cancer the number of moles removed from the skin per skin cancer confirmed has quadrupled in 25 years.

Mass screening is seen as “good” and there are constant calls for more funding for it. The programs attract a “saintly” aura and any questioning will be met with shrill criticism and hostile accusations from the screening industry.

Medical tests have benefits but also costs. The current belief that more is better is not correct. When we are operating on 48 people so one person has a benefit we need to be far more seriously questioning of what we are doing than is currently the case.

Joe Kosterich is a physician in Australia who blogs at Dr. Joe Today.

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