| Leonard Evens 2004-10-04, 2:21 am |
| George Conklin wrote:
> "Leonard Evens" <len@math.northwestern.edu> wrote in message
> news:3JadnTdjDaAYSMfcRVn-uQ@comcast.com...
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> starts
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> Suppose
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> it
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> BPH.
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> Except such studies ARE being done and the results are negative so far.
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Actually not all the study results are what you call negative. The
Swdish study recently reported in the NEJM found a statistically
significant lower death rate from prostate cancer in a group treated by
RP than that in a group treated by watchful waiting followed by hormone
therapy where needed. I'm sure you will also point out that it showed
no statistically significant difference in overall death rates. But
the follow up period was only an average of about six years. So the
information from this study is mixed. It is also of limited use for
comparison with US populations for a variety of reasons.
As far as the studies in the US, since they are not yet complete, one
can't draw any conclusions from them. However, the followup period is
about 12 years. It is then reasonable to suggest that whatever result
they come up with, you would only be safe in using that result if you
expect only to live about 12 years. One has to be careful about
generalizing any study to a population which differs significantly from
the study population. You may say I am trying to prepare in advance
for results showing no effect of treatment, but I think I am just
pointing out the obvious. Your argument is that if no effect shows up
in time T than surely nothing much is going to change after that. I am
always suspicious of people who are sure about things they don't
actually know. I argue that this conclusion follows neither logically
or statistically. Moreover, there have been several prostate cancer
studies which have been shown to be flawed because the chose too short a
time line. That is, there was no significant effect during the chosen
time horizon but later research on the same study population showed a
significant effect with a longer time horizon. So not only can this
sort of thing happen, but in the real world it has happened.
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