When dealing with real world data it is generally true that if you aren't at least somewhat confused about
the details it simply means that there are things you haven't considered. We have touched on a number of topics here where the simple understandings are simple, in part, because they leave things out.
The study at hand shows that men who are selected for the Active Surveillance program at Johns Hopkins are very, very unlikely to die of prostate cancer or even to develop metastatic disease. It's quite a strong result. But also a rather narrow one.
To see what I mean, consider the two titles I have found for this article. In Science Daily it is
"
Some with low-risk prostate cancer not likely to succumb to the disease"
while the title to the Hopkins announcement is
"
Men with Low-Risk Prostate Cancer in Active Surveillance Program Not Likely to Succumb to the Disease, Study Shows"
Notice that the Science Daily title, which seems to be reaching for a broader applicability, doesn't actually
say anything?
Some men with low-risk disease don't succumb? If the term "low-risk" has any meaning then the statement doesn't seem to
need any proof. I like the Hopkins title better because it tells us
which men we are talking about
. Men enrolled in a single, specific Active Surveillance program -- the Johns Hopkins program -- do really, really well.
Presumably, similarly selected men enrolled in similar AS programs also do well but the study under discussion doesn't speak to that. And, actually, when describing the two men who did die of prostate cancer in their study
the article said...
In the second man's case, Johns Hopkins doctors recommended surveillance, but the patient sought monitoring at another hospital and died 15 months after his diagnosis.
so there you go.
The other difficult to understand topic is the "Gleason 6 Never Metastasizes" thing which is even harder to understand. The problem with that one is that it sounds like a statement that looks forward in time but it is actually based on data that looks backwards. A more accurate descript
ion of the result is "If there are metastases present then there must also have been Gleason >6 disease present if you go and look for it."
It is also a very strong result but is almost universally misunderstood.