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You're using outdated information.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.

Yes, his comments on statistics are valid. On a separate note, the
study
showed a small but clear survival advantage with surgery vs. watchful
waiting. We will see what further studies show.


Herman's comment that he would rather go with a study where 3 out of
3
are cured than with a large study showing very small differences. It is
a
valid point. He is in favor a Bayesian methods. Even the New York
Times
had an article comparing the approaches.

I'm not disagreeing, which you don't seem to understand. However, we
don't
have such results. What we have is a larger study showing a smaller
response, but nonetheless, it showed that patients were cured from
surgical
intervention for prostate cancer. Small numbers? Yes. But lives are
lives
so meaningful numbers.

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.

you're living in hypotheticals now. Fact - the study showed a survival
advantage for surgery vs. watchful waiting. It's the best study we
have
right on that topic.

Actually according to what Herman has posted over the years, it is not
hypothetical at all, but a possible artifact.

Yes, an unlikely possibiltiy, but nonetheless a possibility. This is why
multiple studies are being done and why the same study in question will
continue to evaluate their results over the years. The quality of the
study
from this one study was excellent and I find the results believable. If
held true over time and confirmed by other studies, the issue will have no
doubt left. The doubt at this time is minimal.



Here is a comment from UK:

Prostate therapy benefits doubted
Many men diagnosed with low-grade prostate cancer do not benefit from
radical treatment, research suggests.
The researchers calculated that, even without treatment, only about 1% of
men aged 55-59 with diagnosed low-grade disease would die within 15 years.

Side effects of radical treatment such as surgery and radiotherapy can
include incontinence and impotence.

The Department of Health said its advisers would consider the Institute of
Cancer Research findings.

The study appears in the British Journal of Cancer.


The decision whether to have radical treatment can be tremendously
difficult for the patient
Dr Chris Parker

Prostate cancer is the most commonly diagnosed male cancer in the UK.

Nearly 32,000 new cases are diagnosed, and around 10,000 men die from the
disease, each year.

At present, men diagnosed with the disease may undergo radical treatment -
either surgery to remove the prostate or radiotherapy.

Alternatively, they may simply be managed by observation - a technique known
as watchful waiting.

The Institute of Cancer Research team found that radical treatment was only
effective for men with high-grade disease.

In those cases they calculated that, without treatment, up to 68% could die
from prostate cancer.

Difficult decision

Researcher Dr Chris Parker said: "Most men with prostate cancer detected by
PSA screening will live out their natural span without the disease ever
causing them any ill effects.

"The decision whether to have radical treatment can be tremendously
difficult for the patient.

"The results of trials looking at the long-term survival benefit of radical
treatment are several years away.

"So, this new information on the potential impact of treatment on overall
survival will be of great interest to men faced with this decision."

Dr Parker said his team was trialling a new prostate cancer management
technique called active surveillance.

This aims to target treatment only at those who need it by closely
monitoring patients for signs of disease progression.

Preliminary results of this technique have been encouraging.

Types of cell

High-grade prostate cancers are made up of undifferentiated cells, which can
reproduce quickly, speeding growth of the tumour.

Low-grade tumours are made up of differentiated cells which do not reproduce
at the same speed.

Chris Hiley, from the Prostate Cancer Charity, said: "Decision making on
treatment for prostate cancer is not straightforward for anyone involved,
but we hope that these results might make explaining options and possible
outcomes to patients easier for doctors.

"Clearly, some men with a prostate cancer diagnosis will always prefer an
operation to cut it out or radiotherapy to treat the cancer.

"This new evidence shows men mustn't be left to overestimate the survival
advantage that such an option would give them."

Dr Emma Knight, of Cancer Research UK, said: "It is important to stress that
these results are only predictions.

"Data from ongoing clinical trials should, in time, portray the pros and
cons of treatment versus monitoring more accurately."

The Department of Health said the findings would be considered by its
Prostate Cancer Advisory Group.

Story from BBC NEWS:
http://news.bbc.co.uk/go/pr/fr/-/2/hi/health/5012142.stm


.

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