
Trial of a blood test that detects eight common forms of cancer - sjcsjc
http://www.bbc.co.uk/news/health-42736764
======
jamra
One of the things I am hoping for is a general database of cancers and the
mutations they exhibit. By putting them in a database, we may be able to treat
based off the mutation instead of the locality in the body. When my mother was
diagnosed with ovarian cancer, she was given chemo therapy for ovarian cancer
that was unrelated to hers in everything but location. Since her cancer was
very rare, there was no real study that could have helped. If we start keeping
a database, it may help us find new treatments and stop giving dying people
ineffective poisons.

~~~
dekhn
Such databases exist, and they have helped a little, but they barely justify
the investment, so far.

cancer mutations are a complex thing. It's not as simple as: linear
function(vector_of_mutations) -> perfect diagnosis of cancer type.

~~~
sungam
Interestingly it is exactly this problem I am working on!

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TeMPOraL
Tell us more!

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tempestn
This was the most exciting part for me:

 _It was trialled on 1,005 patients with cancers in the ovary, liver, stomach,
pancreas, oesophagus, colon, lung or breast that had not yet spread to other
tissues.

Overall, the test found 70% of the cancers. _

I expected it to be blood cancers only, but this list covers many of the most
common forms of cancer. Could be a huge development.

~~~
AstralStorm
They glossed over the false positive rate...

~~~
Bron101
From other sources
([https://www.medscape.com/viewarticle/891491](https://www.medscape.com/viewarticle/891491))
I was able to find they had a specificity of >99%, with a sensitivity
averaging 70% but was as low as 20% on certain cancers (esophageal cancer).

With such an excellent specificity this sounds promising as a cheap screening
tool, although the sensitivity is too low in some cancer types to be used as a
means to rule out cancer.

~~~
tansey
The problem with the idea of cheap screening tools is Bayes' theorem. If
doctors go ordering this for most people since it's just a blood test, and if
only 1% of people ever really have cancer when tested then the 1% false
positive rate means there's only a 50/50 chance you have cancer given the test
is positive.

~~~
rplnt
So that's one "wasted" advanced screening for one where cancer is found. That
seems great to me.

Also, I assume it would be mostly done on higher risk patients (certain work
conditions, certain age, etc..). Only once in couple of years on younger
population for example. Or if it's really cheap everyone could get it and then
there could be more focused blood screening done next so you don't have to get
full body cat scans.

~~~
vidarh
It's not that simple. If the worst effect was some unnecessary secondary
screening, it would be a no-brainer.

But first of all you need to account for the negative effects of a false
positive, and they are much worse than that. They include anything from stress
and psychological effects, cost and risks of all the additional screening, to
the much worse issue that you also need to account for the fact that for some
cancers in some instances it will be hard enough to determine if the growth is
malignant in the sense that some proportion of cancerous growth will never
pose a threat to the patient, but once diagnosed there tends to be a strong
pressure to treat. As a result too frequent screening will save some, but will
also result in a large amount of unnecessary chemo, radiation therapy and/or
surgeries - all of which come with risks in addition to the pain and
discomfort.

Then you need to account for _frequency_ of testing. A 1% false positive rate
_per test_ looks distinctly worse if the test is repeated every year for a
10-20 year timespan, for example.

Then you'll also want to account for how much it improves _outcomes_. If the
cancers it detects are ones that would generally be detected in time anyway,
and/or have low mortality, and where treatment outcomes are good, the
incremental improvement would not necessarily be big enough to justify the
negatives.

For breast cancer, for example, there has in recent years been a push to
_reduce_ large scale routine mammogram screening because it's not clear if it
does more good than harm for many groups of patients (in large part because it
leads to overtreatment). This article goes into some of the issues related to
that in some detail (and presents both proponents and detractors of large
scale screening):

[http://www.healthbeatblog.com/2009/04/mammography-
screening-...](http://www.healthbeatblog.com/2009/04/mammography-screening-a-
double-edged-sword/)

~~~
rplnt
I'm not sure the pressure to treat is a real issue. Some types of cancers
(lymphoma for example) are only monitored in early stages. So if this would
result in increased early detection, it might be a standard procedure to just
keep an eye on the cancer, even for wider ranges. It's better than waiting for
symptoms to appear (and the tendency for people to ignore the symptoms for a
year before seeing a doctor).

~~~
vidarh
See the link - it includes details about studies done on breast cancer for
example where overtreatment is a real issue. This is not a hypothetical
concern, but a concern that's significant enough that large scale screening
programs have scaled back in some countries in response.

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crb002
The holy grail is a full spectrum metabolome screen that gets a histogram of
both proteins and mRNA.

I expect this in the next five years commercially. It will wipe out almost all
other tests, be available at your pharmacist.

~~~
ipunchghosts
What companies are working on this?

~~~
sjg007
Nobody, it sounds too good to be true.

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lawlessone
Is there a way the general public can help this research or speed it up?

~~~
crb002
Most basic research is there. It is more of an engineering effort to get full
spectrum mRNA and protein histograms cheap and fast enough.

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bitwize
This is next-level badass and here's why: Not only can we detect cancers
earlier and prevent them from getting worse, but if we can _detect_ cancer
cells in the blood, we're that much closer to _killing_ them in the blood,
preventing or mitigating metastasis and improving the treatment prospects for
even later stage cancers.

Go science!

~~~
dekhn
this is a bit optimistic; be aware that press-release-by-science almost always
states near-term impact.

~~~
bitwize
While it's too early to tell, what I'm suggesting is not that much of a
stretch; currently we treat metastasis by dosing the patient up with chemo and
hoping that the dose is enough to effectively wipe out the bloodborne cancer
without killing the rest of the patient. Emphasis on hoping; the trickiest bit
was always detecting small amounts of cancer cells in the blood. At a very
minimum, it will mean more effective and knowledgeable deployment of
chemotherapy, but it's not fanciful to imagine that more easily detectable
cells are more easily targetable cells.

~~~
dekhn
I would strongly suggest you spend a decade in the cancer business before
making claims like this.

