

Why Early Detection Is the Best Way to Beat Cancer - outdooricon
http://www.wired.com/medtech/health/magazine/17-01/ff_cancer

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tokenadult
I read through the article (first published in 2008, it appears) to see what
issues were considered, and what the background of the article author is.
"Deputy editor Thomas Goetz (thomas@wired.com) wrote about the Personal Genome
Project in issue 16.08. He has a new blog about health and medicine at
www.thedecisiontree.com" is what I see at the very bottom of the article. His
blog appears to be updated every once in a while, to promote the article
author's 2010 book.

The article submitted here is a popular article by a layman, and popular to a
fault in that it discusses trade-offs in different screening methodologies,
but doesn't even introduce the reader to important concepts like sensitivity
and specificity of medical tests.

<http://en.wikipedia.org/wiki/Sensitivity_and_specificity>

It's very important that HN participants digest the article kindly submitted
here with a compare-and-contrast reading of "The early detection of cancer and
improved survival: More complicated than most people think"

[http://www.sciencebasedmedicine.org/index.php/the-early-
dete...](http://www.sciencebasedmedicine.org/index.php/the-early-detection-of-
cancer-and-improved-survival-more-complicated-than-most-people-think/)

by David Gorski, M.D., an experienced cancer researcher and experienced
blogger about science-based medical decision-making for popular readers. His
conclusion, "The bottom line is that the ever-earlier detection of many
diseases, particularly cancer, is not necessarily an unalloyed good. As the
detection threshold moves ever earlier in the course of a disease or
abnormality (in the case of cancer, to ever smaller tumors all the way down to
the level of clusters of cells), the apparent prevalence of the disease being
screened for increases, and abnormalities that may never turn into the disease
start to be detected at an increasing frequency. In other words, the signal-
to-noise ratio falls precipitously," is a necessary caution in predicting the
benefit of early detection of what appears to be cancer.

The American Cancer Society has a good 2012 publication, "Cancer Treatment &
Survivorship: Facts & Figures 2012-2013"

[http://www.cancer.org/acs/groups/content/@epidemiologysurvei...](http://www.cancer.org/acs/groups/content/@epidemiologysurveilance/documents/document/acspc-033876.pdf)

that provides more details on what it means to survive a case of cancer.

~~~
danielweber
David was the one who taught me about the Will Rogers phenomenon. Merely by
reclassifying something, you can make it look like all categories improve,
while overall no improvement happened.

[1]<http://en.wikipedia.org/wiki/Will_Rogers_phenomenon>

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bryanlarsen
There are huge drawbacks to early detection, though. Surgery, radiation
therapy and chemo-therapy are very invasive techniques, doing huge amounts of
damage to a person's body as well as to the cancerous cells. It very often is
the case that the cure is worse than the disease. Early detection also submits
people to the huge mental stress of thinking that they're going to die soon.

And that's the case even if the early detection techniques were perfect. They
aren't, far from it. They have a significant false positive rate. Many people
who don't have cancer are subjected to the mental and physical stresses of
cancer treatment. They then think that this treatment saved their lives, so
they say to everybody they know: go get tested!

The other problem is the prevalence of cancer. 80% of men in their 70s have
prostate cancer. Some of them will die from it, but most will die from heart
disease or another cause. Treating them for prostate cancer will cause a huge
decrease in their quality of life for no benefit.

Yes, early detection of cancer is a very potent tool for saving people's
lives. But it's not a panacea.

[EDIT: the article actually does discuss most of these issues, I just wanted
to try and balance things. Read the article.]

~~~
brazzy
> Surgery, radiation therapy and chemo-therapy are very invasive techniques

A not so well-known fact to drive that home: cytostatics (the bulk of
traditional chemotherapy) are derivatives of some of the nastiest chemical
weapons developed in WWI, specifically mustard gas.

~~~
elemeno
More than that, Mustard Gas was fairly important in the development of
chemotherapy after US Army Doctors noticed it's effect on white blood cells
following an air raid in WW2 when a ship carrying Mustard Gas was bombed. From
there, in part, was sparked the idea of using similar drugs to attack cancers.

[http://www.the-
hospitalist.org/details/article/243771/From_W...](http://www.the-
hospitalist.org/details/article/243771/From_Weapon_to_Wonder_Drug.html)
[http://en.wikipedia.org/wiki/Sulfur_mustard#Development_of_t...](http://en.wikipedia.org/wiki/Sulfur_mustard#Development_of_the_first_chemotherapy_drug)

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jredwards
There are a number of reasons why early detection is often oversold as a way
to improve survival rates (which is not to say that early detection is bad, it
just might not always help). The article doesn't seem to reference all of them
directly, though I'll admit to skimming a bit. Here's a brief list,
paraphrased from here: <http://www.ncbi.nlm.nih.gov/books/NBK20938/>

Lead-Time Bias: The earlier you detect, the earlier the clock on your survival
starts. 5/10 year survival rates go up simply because the cancer is at an
earlier stage when we started tracking how long people survive, not because
early detection necessarily lead to more effective treatment.

Length Bias: More screening means a higher probability of finding cancers
which would have stayed relatively benign for a very long time (as opposed to
cancers presenting very obvious symptoms). Survival rates appear to go up
simply because you're detecting less threatening cancers. I believe the
article references this idea.

Overdiagnosis: Heavy screening means finding cancers that may never have
become threatening at all (as the referenced link states, an extreme example
of length bias). Survival rates go up, but not because screening helped. It's
been suggested that countries which screen more often have better survival
rates simply because they find cancers which would have benignly resolved
themselves and gone unnoticed in countries which screen less often.

Patient Self-Selection: Patients who seek out screening may be more likely to
live healthy lifestyles.

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hooande
I've long thought that machine learning would be a great tool for detecting
cancer and other diseases. There is a small but growing body of research to
support this idea, but very few practical implementations. [1] [2] [3]

Ultimately detection is an issue of pattern recognition, and computers are
really good at that. The two biggest barriers are the amount of data that
needs to be collected and annotated, and the sensitivity of medical data. If
someone reputable were to start a large scale data collection effort, we could
make huge strides toward identifying some of the key cancer indicators. It
would even benefit people who can't afford top quality medical care (servers
are cheaper to deploy than doctors).

Cancer is the ultimate medical opponent. It comes in so many forms and can
change into so many more. Many cancers spend 10-20 years as harmless lumps of
cells before doing any serious damage. It seems like the best bet is to every
tool available to find them long before they become a problem.

[1] [http://cs229.stanford.edu/proj2011/Planey-
Machine%20Learning...](http://cs229.stanford.edu/proj2011/Planey-
Machine%20Learning%20Approaches%20to%20Breast%20Cancer%20Diagnosis%20and%20Treatment%20Response%20Prediction.pdf)

[2] [http://www.mendeley.com/research/data-analytic-strategy-
prot...](http://www.mendeley.com/research/data-analytic-strategy-protein-
biomarker-discovery-profiling-high-dimensional-proteomic-data-cancer/)

[3] [http://www.popsci.com/science/article/2011-11/new-
computer-m...](http://www.popsci.com/science/article/2011-11/new-computer-
model-examines-breast-cancer-better-doctor)

------
bill_from_tampa
The concept of early detection or screening is very attractive, but for many
cancers the results have been disappointing:

Prostate cancer: (not effective)
[http://summaries.cochrane.org/CD004720/screening-for-
prostat...](http://summaries.cochrane.org/CD004720/screening-for-prostate-
cancer)

Breast cancer: (evidence conflicting, minimal improvement)
[http://summaries.cochrane.org/CD001877/screening-for-
breast-...](http://summaries.cochrane.org/CD001877/screening-for-breast-
cancer-with-mammography)

And as other commenters have noted, early detection does not mean the ultimate
outcome will be improved -- some cancers have a spectrum of presentations,
with some persons having more slowly growing / indolent tumors that can be
detected and treated (but may not have actually been likely to harm the person
harboring the lesion), while other persons develop rapidly growing and very
aggressive tumors that will be fatal (but are hard to detect with screening
because they develop and spread rapidly). Only carefully constructed and
controlled studies can determine if screening for a particular cancer with a
particular screening test actually improves survival or reduces morbidity --
short term or uncontrolled studies can be very misleading.

Also the whole subject is subject to anger and political correctness issues --
some good hearted persons want to believe that some screening metholodogy must
help because they want it to help, the evidence be damned! So there can be
more heat than light ... anybody who says a specific screening test not
helpful can be accused of running a "death panel".

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mikenuman
In the case of ovarian cancer, as described in the article, it's likely that
"early" ovarian cancer is a separate disease from disseminated ovarian cancer.

Assuming that one leads to the other has lead to a large research effort that
has failed to help. Screening is ineffective at best, and probably harmful as
it:

picks up the earlies that would have been detected and cured in an ad hoc
fashion; picks up a host of benign pathology, removal of which leads to
iatrogenic harm; fails to pick up aggressive cancer which spreads almost
immediately and may even arise in multiple locations at the same time.

The current best methods for prevention are using the contraceptive pill,
removing the Fallopian tubes (50% of "ovarian cancers" are probably tubal),
and removing the tubes and ovaries of people in high-risk families after
childbearing.

Screening does not work.

~~~
elemeno
Sources to back up the idea that early stage ovarian cancer is separate from
late state ovarian cancer?

~~~
bryanlarsen
The article mentions the hypothesis that the particularly malignant ovarian
cancers are actually fallopian cancers that have spread.

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carbocation
My unfounded $0.02 is that the best way to beat cancer is the same as the best
way to beat HIV: multidrug targeted molecular therapy to prevent resistance.
This is currently mostly a pipe dream as our targeted molecular therapies are
few.

Early detection is useful if you can treat appropriately. Early detection of
HIV (where 'early' means no AIDS-defining illness) is an example here. Early
detection is a tool, but it's not the point. It's the debates, but not the
election.

Again, I am not a cancer biologist but the parallels have long struck me. The
goal IMHO is to make cancer a typical chronic disease that you live with but
can tolerate for decades. Perhaps I am not dreaming big enough, but I think
this would be a huge stepping stone. If you can cure a cancer already, of
course, by all means do so.

~~~
jhuckestein
The problem with cancer is that, much like with the HIV virus, the immune
system is fooled into thinking the cancerous cells are part of the human body.

From what I hear researchers are optimistic that any such disease can soon
(i.e. within the next 20 years) be cured by injecting blood-cell sized
nanobots that can reliably target the foreign cells or viruses in your body
and kill them (and, unlike chemotherapy, don't destroy the good parts, too). I
think the chronic disease is just a crutch that'll soon be obsolete.

~~~
jamesjporter
Cancerous cells are part of your body — they've just mutated such that they
don't respond to signals that tell them to die or slow their rate of
replication. The reason your immune system doesn't recognize them is because
they are literally part of you. This is why specifically targeted cancer cures
are so hard: there's almost nothing that distinguishes cancer cells from
normal cells.

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ImprovedSilence
Single Page Version:
[http://www.wired.com/medtech/health/magazine/17-01/ff_cancer...](http://www.wired.com/medtech/health/magazine/17-01/ff_cancer?currentPage=all)

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outdooricon
The article concludes with the hope that Contrast-Enhanced Ultrasound (CEUS)
could be extremely useful as another step towards reducing false-postives.
This article was written in 2008 and even though it's 4 years later, according
to the Canary Foundation's website (
[http://www.canaryfoundation.org/research/ovarian-cancer-
clin...](http://www.canaryfoundation.org/research/ovarian-cancer-clinical-
studies/) ), they are STILL waiting on FDA approval for the CEUS
microbubbles...

