Medical Screening- More Not Allways Better

There is a great line in the movie Men in Black when Agent K (Tommy Lee Jones) is telling soon to be agent J (Will Smith) about aliens on the planet which until then J had no knowledge of. It goes like this - “ 1500 year ago people knew that the earth was the centre of the universe, 500 years ago people knew the earth was flat, yesterday you knew there were no aliens on earth what will you know tomorrow?”

Now I am not entering into a discussion about aliens but the real point is that our knowledge changes. This mainly happens through trial and error and also through creative genius. The medicine man in the seventeenth century applying leeches didn’t think he was doing the wrong thing. He was going with the knowledge of the day.

Today science is able to make greater progress than in centuries gone by. However it remains an extension of trial and error. The simple reason for that is that science is an extension of our senses and capacity to interpret what we find. Before the invention of microscopes we couldn’t see bacteria-it didn’t mean they weren’t there. Before the electron microscope we couldn’t see our genes (DNA) –again it didn’t mean it wasn’t there.

Science then is limited by the five senses and an assortment of aids such as microscopes. More importantly scientific discovery is a reflection of our capacity to “understand and interpret” what we find. Ultimately what we “know” today may be found to be totally wrong tomorrow. This is how knowledge advances.

The recent furor over cancer screening fits into the above scenario. In the USA new guidelines for mammograms now recommend that it be done two yearly starting at age 50 rather than annually starting at 40(this now matches Australian guidelines) .The new guidelines comes from looking at the actual results of the screening program. New guidelines are also being considered for cervical cancer screening. Prostate cancer screening remains highly controversial as to what is best.

It is easy to paint all cancer screening as “saving lives” and dismiss the problems. However screening can lead to unnecessary procedures (including surgery) and stress for people who have false positive results (results which show an abnormality but where the person has no disease). Also we are seeing that some very early “cancers” might not actually develop and some resolve themselves.

Now none of this is to say that screening is not helpful. It is to say that what we “knew” ten years ago may no longer be relevant. It is also important to note that the loudest arguments against change usually come from those who are doing the screening. They necessarily have a vested interest, which may be financial or reputational. The medical industrial complex has spawned industries around screening and follow up treatment.

Sadly this debate may get tied up in arguments about payments and “rationing”. More tests have been seen as being only positive. The reality is that indiscriminate testing has downside. Whilst it is easy for a person to say “my cancer was found and I don’t care how many other people had needless tests and stress to allow this”, that is only one side of the issue, albeit the only side that gets much airtime. Furthermore real questions can now be asked as to whether all these cancers would have progressed anyway. In other words it may not be the screening that “saved all the lives.”

As our knowledge grows and more importantly our capacity to understand what we “see” grows there will be changes in what is regarded as best medical practice. These should always “challenge “ current ideas and generate debate. Clinging to what has been done before when new knowledge supersedes it is the modern equivalent of insisting the earth is flat.