

Study of 160k men finds no all-cause mortality benefit from prostate screening - carbocation
http://www.nejm.org/doi/full/10.1056/NEJMoa1113135

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streptomycin
To clarify the Hacker News title, the article is talking specifically about
prostate-specific antigen (PSA) screening, which is already known to be of
uncertain medical value except in some very specific situations. As the
discoverer of PSA said, "I never dreamed that my discovery four decades ago
would lead to such a profit-driven public health disaster. The medical
community must confront reality and stop the inappropriate use of P.S.A.
screening. Doing so would save billions of dollars and rescue millions of men
from unnecessary, debilitating treatments."
<http://www.nytimes.com/2010/03/10/opinion/10Ablin.html>

There are other more promising methods of prostate cancer screening in
development that will hopefully be able to do better in the future.

~~~
bermanoid
From the link you posted:

"last month, the American Cancer Society urged more caution in using the test"

It's a very sad state of affairs when a test that unambiguously offers some
statistical utility (speaking as a Bayesian, _any_ test is useful if we do the
right things with the results, this is quite literally a provable theorem of
decision theory) is potentially problematic because we aren't properly
evaluating what to do when we get the results. I can't blame patients here,
they're not the experts; it's doctors (and perhaps more fairly, the entire
medical research industry) that need to wise the fuck up and realize that
they're acting as statistical dilettantes in a field where they're putting
patients lives at risk because they don't understand math very well.

Yes, even a test that only detects ~3% of cancers should be useful; but this
requires that doctors completely understand what it means both to see a
positive and a negative result, and don't overreact when they see either one.

If this was a matter of just weighing the costs of having tests done versus
the benefits of getting the results, it would be one thing. But it's not.
People actually end up suffering and spending great amounts of money just
because they did "the right thing" and had tests run, and then listened to the
doctors' advice afterwards.

Once more with feeling: after discounting for the cost of the test, there is
no test that should be of negative value for a rational agent to take. The
results should _always_ be used in a way that, in general, increases the
welfare of the people taking the test.

If this is not the case in medicine, then they're doing something seriously
wrong mathematically speaking, and this is a very bad thing that should be a
high priority to fix.

~~~
Sniffnoy
Unless taking the test has a cost in and of itself -- such as if it requires
surgery, so that the risk of something going wrong during testing might
outweigh the information gained if the condition being tested for is rare.

~~~
bermanoid
Yup, definitely, I should have made that more clear than it was (I did mention
"after discounting for the cost of the test", but it wasn't as obvious as it
should have been). Test costs have to be weighed against benefits, but that
whole process involves a lot more statistical sophistication than is typically
applied in practiced medicine. Researchers are slightly better, though it's
fairly common even for them to make hideous statistical mistakes, which is a
real problem in the field.

IMO, if pre-med requirements included a bit more statistics and a bit less
biology, we'd all be better off...

~~~
Sniffnoy
Ah, I missed that you included that.

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fishtoaster
It looks like this is the 2 year follow up to a previous study.

"Analyses after 2 additional years of follow-up consolidated our previous
finding that PSA-based screening significantly reduced mortality from prostate
cancer but did not affect all-cause mortality. "

So, if I follow this correctly, your odds of dying from prostate cancer are
still definitely lowered by screening, but your odds of dying overall are not.
Perhaps this indicates that people who would have gotten prostate cancer are
the sort of people (via lifestyle, genetics, diet, etc) who would die of
something else anyway.

~~~
bryanlarsen
Somebody correct me if I'm wrong, but here's the way I understand it. One of
the major problems with PSA-based screening is false-positives. Getting a
false-positive result for cancer could certainly increase your risk of an
early death. Cancer treatments put a lot of stress on you physically, and the
diagnoses could also cause a lot of mental/emotional stress. Stress of either
kind reduces life expectancy.

~~~
bermanoid
False positive rates should be understood by the doctors that recommend
treatments, though. A doctor _should_ be able to accurately tell a patient
what the chance is that they suffer from a disease based on a positive result
from a test.

Unfortunately, doctors tend to be terribly bad at this - they are generally
quite inept at incorporating prior probabilities into the estimates, and
assume that (for instance) if a test has only a 1% false positive rate, then
that means a positive result means it's 99% certain that you have whatever
it's testing for.

If it's not immediately obvious why that's an idiotically dangerous
assessment, then you need to think a bit about a rare disease that only shows
up in 1 out of a million people, and then consider the 10,000 people that will
test positive for it at a false positive rate of 1%. Don't worry, most doctors
don't get this right at first, either, and they will happily suggest to all
10,000 of those people that they seek aggressive, even life-threatening
treatment...the difference, of course, is that they're goddamn doctors,
entrusted with keeping people alive, and they really ought to know better,
whereas you're just some person on the Internet.

~~~
carbocation
A classic systems problem. If something is this important, you don't leave it
up to the decision of thousands of inhomogenous physicians. You create a
system that ensures they don't even get to choose to get it wrong.

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awakeasleep
If you're interested in how our ability to detect cancers (and other diseases
like diabetes and osteoporosis) has surged ahead of our ability to know when
treatment is effective, I highly recommend Overdiagnosed by Welch, Schwartz,
and Woloshin.

Right now medical science seems to be at an uncomfortable phase with certain
diseases where we can't be sure our treatments will have a greater benefit
than the cost of the treatments— and not just in terms of price, but at the
expense of our health itself.

[http://www.amazon.com/Overdiagnosed-Making-People-Pursuit-
He...](http://www.amazon.com/Overdiagnosed-Making-People-Pursuit-
Health/dp/0807022004)

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waveman
Actually there _was_ a reduction in all-cause mortality. It's just that the
study's design was such that the reduction could possibly have been due to
chance. This is _not_ at all the same thing as "finding no ... benefit".

This lack of statistical significance is probably mainly due to the small size
of the study (160 men).

Note that the reduction in death rates from prostate cancer was large in
practical terms and (statistically) significant.

Prostate cancer kills a minority of men. Take this fact, add in the fact the
study was small, and then throw in all other causes of death (which vary
randomly) then it is not at all surprising that the result was not
_statistically_ significant. This is mainly due to a small study and noise
from other causes of death.

I for one am going to keep having my PSA tests.

~~~
waveman
Having said that, the state of Prostate Cancer treatment and the lack of
research into Prostate Cancer is a disgrace.

Prostate cancer kills similar numbers to breast cancer yet gets half the
research funding. Thank goodness we live in a patriarchal society or the ratio
would be even more in women's favor.

I have watched two male relatives die of Prostate Cancer and it is not a good
way to go.

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pagekalisedown
For those unfamiliar with the term "all-cause mortality":

[http://answers.yahoo.com/question/index?qid=20090813211127AA...](http://answers.yahoo.com/question/index?qid=20090813211127AATsc0e)

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Alex3917
Thank you for phrasing this in terms of all-cause mortality. If only every
academic study (and submission) used this as a metric, the world would be a
vastly better place.

~~~
niels_olson
I doubt it. If you relied on all-cause mortality for every study, you'd never
get out of phase I trials.

~~~
veguss
Majority of "drugs" do not improve outcome. They "improve" condition.

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veguss
Put another way, prostate screening does not improve outcome at all. In fact,
given the horrible treatment involved, it degrades life quality while not
improving outcome.

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velus
"Modern medicine" is in the stone ages due to the profit motive. Cure stops
all income while "treatment" keeps the money coming in.

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drivebyacct2
Seems like these results could be unfortunately easily misrepresented or
misunderstood by people.

