We have to decide medical diagnostics and treatment on science. And science changes.
Medicine is an odd conglomeration of art, science, and common wisdom. The science part keeps getting bigger as studies are done to determine the effectiveness of various procedures. The art part will never go away, because we're dealing with issues that weigh heavily on people's emotions. But the function of that art will move toward comfort and persuasion, less in decision-making.
The common wisdom part was a foundation of medicine. People found that certain herbs and actions helped with diseases and other conditions, like broken legs. They combined that knowledge and passed it on. Some of that was a process like science, in which stuff was tried and note taken of whether it worked or not. But without scientific rigor, other sorts of things, like "I've always done it that way" kick into the common wisdom. As Ezra Klein reminds us, leeches were once a staple of medicine. Sometimes the blood loss from their treatments killed the patient, but hey, they were sick and probably would have died. Or maybe they died from what the leeches were treating them for.
Science is a more reliable guide. One of the tools it relies on is risk assessment, which is particularly difficult to communicate because it's counterintuitive.
We'd like our experts to give us certain and simple advice on health matters. But that's not the nature of science, particularly medical science. Individuals are different, and we don't know enough about cancer to be definitive.
A friend has gone through treatment for serious breast cancer. She keeps asking her doctor to tell her that the cancer is gone. Instead, the doctor tells her that the cells are circulating in her body, and what has to be done is to keep them from settling and making new tumors. My friend understands intellectually that that's probably correct, but emotionally she will keep asking the doctor to settle this question once and for all. And, of course, what she wants to hear is that yes, her body is totally free from cancer.
Many women thought that the previous guidlines on mammography were definitive. But mammograms don't catch every cancer, they see things that look like cancer but aren't, and they expose your breast to a tiny bit of radiation that ups the probablity of cancer later on by a tiny bit. Those are the considerations in this latest study, along with the outcomes of all that mammography. And the result is that mammograms aren't all that harmful. The same for doctors teaching women to examine their own breasts.
I haven't read the report, but it doesn't say that women should never check their breasts, as some (here and here) are taking it. I suspect that it says that doctors teaching women to check their breasts doesn't do much good. That may well be because many women are pretty conscious of what's going on in their bodies anyway and those who aren't don't change because their doctors tell them to.
And now a new recommendation on Pap smears. More hollering to come.
The guidelines for prostate-specific-antigen tests were cut back similarly a few months ago without all this noise. And I am wondering if these people who are so fond of testing have a colonoscopy every year, plus blood tests for leukemia and tests for all the sorts of cancer that there are. I am sure that there are many people who will attest to a colonoscopy's having found a cancer early and saving their lives.
The idea of detecting and treating cancer early was a success of public education. So far (and it's early), the medical profession isn't doing such a good job of educating to these new results. In fact, a number of doctors have firmly stated their intention not to change what they've been doing. Here are some better attempts, from the president of a medical-imaging firm; a woman who, like me, wonders about her diagnosis; a scientist who has looked at these matters for some time; the New York Times editorial board; a historian of science; and, of all people, Steven Pearlstein*.
*With the exception that the saying is "the plural of anecdote is not data." That appears to be what Pearlstein intended, but he got it wrong.