Middle Medicine

The Archives of Internal Medicine published an article this week which challenges the conventional wisdom regarding the early detection of breast cancer.
This bit of research is an excellent example of what RCTs are good for: examination of apparently homogeneous populations to find indications of non-homogeneity.
Two groups were studied – women with frequent screening (and their cancer rates), and women with infrequent screening (and their cancer rates). The researchers were astounded to discover that, in these two large groups of people (approx 100,000 each), there was a twenty two percent greater incidence of cancer in the women who were screened frequently[1].
There are many explanations for this phenomena – the one that the authors advance is that a certain proportion of tumors go away “on their own” (although this author is certain it is not quite that random or mysterious).
If we read the USA Today article, we can find an interesting statement by the cancer society’s Robert Smith: “It’s important that people not wonder if women lost their breasts for no reason. That’s a reprehensible conjecture.”
Mr. Smith, medicine is not about feel-good. It’s about finding the correct way to maintain health and the correct way to resolve disease. Avoiding a conjecture because of a bad feeling is bad medicine. Conjectures should be based on the best available data and followed accordingly.
And, yes, unfortunately, human life does seem to have quite a bit of uncertainty and ignorance built-in.

From the study:

Conclusions Because the cumulative incidence among controls never reached that of the screened group, it appears that some breast cancers detected by repeated mammographic screening would not persist to be detectable by a single mammogram at the end of 6 years. This raises the possibility that the natural course of some screen-detected invasive breast cancers is to spontaneously regress.

Why the fear that cancer can be cured? Why not just write that the evidence indicates that the body is able to heal some cancers on its own some of the time?

The fear, in this case, doesn’t help us.

There is another possibility, which is the one that the spokesman for the cancer society immediately assailed: is it possible that the search and treatment for cancer causes more cancer?

It would seem that, if this is the case, the fear definitely doesn’t help us.

1.The natural history of invasive breast cancers detected by screening mammography.  Arch Intern Med. 2008 Nov 24;168(21):2302-3.