Re: Medical Research-Evidence


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Prostate cancer treatments are being evaluated, such as
the
PIVOT
study. But some going on for 10 years have yielded no
results
yet,
strongly
suggesting that all current modes of treatment cure those
who
would
not
die
of the disease anyway. Those who advocate PSA tests and
aggressive
treatments now claim that the best results will show up
AFTER
15
years!!!
But that is another 5 years out, and then it will be raised
to
20.

There is recent 10 year data showing a survival benefit of
surgery
vs.
watchful waiting. It's long been known that survival benefit
studies
would
need to go out at least that far except in metastatic cases.



Here is a comment from another newsgroup:

Both Dale and George are correct.

Dale is correct in that radical prostectomy has been shown to
lower
the
death rate due to prostate cancer (see the New England Journal
of
Medicine article at:
http://content.nejm.org/cgi/content/abstract/347/11/781).

George is correct in that radical prostectomy has been shown to
have
no
significant difference over watchful waiting in overall
survival
(see
the New England Journal of Medicine article at:
http://content.nejm.org/cgi/content/abstract/347/11/781).

Now, what do you have to add with a link?

You're using outdated information. That study had a mean
followup
of
only
6.2 years, which was too short for a survival study with prostate
cancer.
Allow me to refer to a followup the same study you posted above,
done
with
the same patient population and the same authors, just longer
timepoints
for
data:

3 years later, a newer/better study was published in the same
Journal:

"Radical Prostatectomy versus Watchful Waiting in Early Prostate
Cancer",
May 12, 2005 by Bill-Axelson and Holmberg et al. (same authors,
longer
followup)
This paper is *the* landmark paper for this topic in the field.

The study showed that "radical prostatectomy reduces
disease-specific
mortality, overall mortality, and the risks of metastasis and
local
progression".


and then the following, which is what Herman talks about
allowing
the
patient to make decisions:

You're welcome for the reference.

"THE ABSOLUTE REDUCTION IN THE RISK OF DEATH AFTER 10 YEARS IS
SMALL...."

The risk of death was not seen at 6 years, which was to be expected.
3
years later it was noticed - before it should have been expected to
be
seen - and was both clinically and statistically significant. The
more
time
that elapses, the more signficant the differences will become.


This was expected for high-dose chemotherapy for recurrent breast
cancer
too, but it did not work out that way. (The so-called bone marrow
transplants).

Even if the results get no better than they are now, their is a
signficant
difference, clincally and statistically.

What Herman was trying to tell you is that this is not so.

Herman is not a a doctor and a physician is in a better situation to
determine what is CLINICALLY significant.


You remind me of the Catholic church when it came up with a marriage
questionnaire. It could not be looked at statistically because it was a
holy document.

Clinically as used by your is a mystification technique. It is
meaningless. The only issue is whether a treatment works.

What Herman was trying to tell you is that in decision theory he would
rather trust a treatment which cured 3 out of 3 than 2% more of a large
group of people. Why? Well, too many variables not controlled for. What if
they go back now and find that those who were 'cured' were only those who
did NOT have the newly-discovered gene? Or did have? Or what? Very small
differences in cancer survival rates over very long periods of time may be
significant at the .05 level, but relatively meaningless at the individual
level. When effectiveness is unexplained, then Herman brings up a valid
point.



Very small
differences must be evaluated carefully even if statistically
significant.
The original authors state differences are small. Why dispute them?

I'm not disputing them. I support them. You just don't seem to
understand
that a relatively small difference can be a very important one...
especially if you're amonge the extra 20 lives saved in that study.


The problem is that when you rerun the study, with low levels of
significance you might just as well find the opposite, as the HRT studies
showed or seemed to show.



I'm not one of those guys who advocates prostatectomy for every
patient
with
prostate cancer. I think there are a large number of patients for
whom
watchful waiting is appropriate. However, we can now say,
conclusively,
that in the face of diagnosed prostate cancer, surgery will save
lives.

Well, if you believe the data, a few. What about surgical
mortality?
Did they happen to include that?

Of course. If I recall, there we no reported deaths. I'm at an
institution
that does about 5-10 per week and I can't recall the last time we had a
mortality from this surgery. But yes, mortality was included and
should
always be inlcuded in such outcomes studies.

OK.

As for believing the data, I'd hope you would believe, since it was
merely
an extension of a study that you believed enough to post a link to.


I read the article, and noted that the differences are small. I
wonder
why the American studies are holding back their results.

See below, they just finished enrollment a few years ago, which is about 5
years after the Euro study finished enrollment. That's why.


I understood that 8 years should be enough for preliminary results. The
Euro study rushed into print with that time frame. The USA PD said nothing
had emerged so far, at least on the radio. I am assuming silence since then
makes the same conclusion hold.


Just a few
differences in classification of deaths in the study you cite would
change
the results.

Yes. It may have lessened the results. Or it may have strengthened them.

When multiple causes of death are present, a committee
decision that death was due to disease 1 or 2 is highly subjective.
Those
comments were widely discussed at the time the study was released.

All cancer survival studies have this problem - so while I agree that it
is
an issue, it's not one we can avoid. I could, of course, use the same
argument to say there may be differences in studies that didn't show a
difference for this very reason... but since there isn't a good way around
it, I leave it alone. So should you.


So much depends on the age of the patient and how many other confounding
diseases are present. That is one reason why Herman thinks that decision
theory is important and raw levels of significance are NOT. Yet you in
different posts said you cannot compare nations. So how can you object to
much more immediate concerns?



The American studies

Are not done yet.

are 10 years old and have no released their data
yet. Had they found even 1% differences, they would have gone to the
press
and hollared loudly. The PIVOT studies seem silent too. Why? No
results.
There were a lot of other questions raised by the Scandinavian data
too
last
year.

FACT:
The Euro study completed enrollment in 1999. PIVOT just completed
enrollment 2 or 3 years ago. The data are far too immature and won't
be
ready for a few more years.


On NPR there was a study from a man who called it the "Minneapolis
Study,"
as I recall, and it had been going 8 years with no results. The study
director was interviewed. I did not have a tape machine going.

You can speculate all you want. The FACT is that the study close
enrollment
a half decade later than the recently published Euro study, so their not
having results yet is entirely expected.


8 years was enough time for the Euro study to rush to print.


The study showed 30 men dying of prostate cancer in the surgical
arm
with
50
men dying of prostate cancer in the watchful waiting arm. The
total
number
of deaths from other causes were 53 and 56, resepectively - so
equivalent.

For Herman - that is both statistically and clinically
significant
:)

These numbers will likely to become even more disparate between
the
two
groups as time goes on, since that is the nature and natural
history
of
prostate cancer. In truth, this study found a signficant
survival
advantage
a few years earlier than most had predicted.

So you can tell your poster in the other newsgroup his data is
outdated
and
now you, George, have been given evidence that early intervention
prostate
cancer saves lives.

Good day.

And let me remind you a point I made earlier: the progress
against
adult
cancers is SMALL.

That's an opinion, one that I don't share.

You even gave me an article which said small. What you boys do in
the
medical business is inflate your egos. You are such a prime example.

First, there is more to progress than survival.

No one said there was not.

Then we have made "progress against cancer:"


What? Side effects of treatment for prostate cancer are very severe too,
in some cases very, very severe.


The ability to treat the
crippling symptoms of metastatic disease beyond cure is of major
importance.

That was said about high-dose treatment of breast cancer too, but it
turned out maybe not to be true.

I don't know your hangup with breast cancer. Palliative hormonal
treatment
for prostate cancer has been around for decades and is very effective. If
you want to debate breast cancer, start a new thread.


I have argued elsewhere that women are 25 years ahead of men in
demanding the proper studies. HRT studies also were done that finally
showed how awful self-selection has been in the medical literature. Men are
always offered a 'choice' of treatments (or at least some are), so outcomes
are always self-selected in most of the studies.


Second, prostate cancer is just one cancer, and given the indolent
nature
of
it and other factors it will never be the poster child for progress in
cancer. However, there are HUGE surival differences if you look at
other
treated vs. untreated cancers such as bladder and kidney.

Huge, as in how much added life expetancy? Surgical removal of a
kidney
as opposed to what? Doing nothing? I was more interested in the
prostate
cancers because my father was treated at 65 and died at 90 from
something
else. (Radiation). He taught 38 years of premeds so had a lot of
doctors
to choose from that he had had as a student.

Prostate cancer is very different from kidney cancer. Survival will be
more
difficult to show, it will take much longer studies, etc. Kidney cancer
or
bladder cancer is quite the opposite. If not treated pronto, either can
progress rapidly to death. Surgery can result in cures in large numbers
of
patients, espeically lower stage disease. The numbers depend on the type
of
cancer, the stage, the treatments, etc. But there is not the same
controversy as there is with prostate cancer - with renal and bladder
cancers rapid surgical intervention clearly can be life saving for many.

Well, at least for some. Unfortunately until the biology of prostate
cancer is figured out, we are left with treatments which have yielded
'small' results either way. I guess you have to stick to being an optimist
but very very slow 'progress' with adult cancers shows that in general
medicine is not going to cure people with surgery on the prostate, or at
least few. We all know people with low-grade prostate cancers who died
about 7 years after their radical operations, right 'on schedule' if you
will.


.

Relevant Pages

  • Re: Medical Research-Evidence
    ... "Radical Prostatectomy versus Watchful Waiting in Early Prostate ... The only issue is whether a treatment works. ... differences in cancer survival rates over very long periods of time may be ... advantage for surgery vs. watchful waiting. ...
    (talk.politics.medicine)
  • Re: Medical Research-Evidence
    ... What Herman was trying to tell you is that this is not so. ... The only issue is whether a treatment works. ... the discovery of a gene which contributes to prostate cancer means that all ... about adding in gene information about prostate cancer is just one example. ...
    (talk.politics.medicine)
  • Re: Delayed Treatments for Prostate Cancer
    ... "Incidence of Initial Local Therapy Among Men With Lower-Risk Prostate ... Cancer in the United States "? ... It was a retrospective review of thousands of patients in the SEER database. ... Treatment may result in morbidity. ...
    (talk.politics.medicine)
  • Re: Delayed Treatments for Prostate Cancer
    ... "Incidence of Initial Local Therapy Among Men With Lower-Risk Prostate ... Cancer in the United States "? ... Treatment may result in morbidity. ...
    (talk.politics.medicine)
  • Number of prostate biopsies
    ... "If during an DRE the uro feels a nodule, is it really necessary to take more than one biopsy, right from the nodule? ... There could be cancer even if no nodule was felt. ... The importance in taking multiple cores from around the prostate is in determining the percentage of cores which show up positive for prostate cancer. ... Basically, if 50% or more come up positive, then there is almost no chance that localized treatment will effect a cure. ...
    (sci.med.prostate.cancer)
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