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Blood test that finds 50 types of cancer is accurate enough to be rolled out

theguardian.com

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Re: Blood test that finds 50 types of cancer is accurate enough to be rolled out

#271

Post by jghn »

rackjack wrote: post #238
function_seven wrote: post #216

Earlier quoted context omitted.

If they aren't mass collecting this data in the first place (for the reasons outlined above), then how can they be doing this? Or, if they are doing this from quality samples of the population, then we have data to show that, for example, "Yes, Mr. Function Seven, your scan shows elevated levels of Widget-5a enzymes. This is often a precursor to Gadget Cancer, but 30% of the population shows this elevation, while onl…

They are mass collecting the data. They have more data than they know what to do with. Bioinformatics abuses data science at levels comparable to Google and Facebook. They are getting quality samples from the population. But it's not a simple as "high enzyme = maybe good chance of cancer". How are you going to get those enzymes from their blood in a way that can be applied to the general population? Before that, how…

> Bioinformatics abuses data science at levels comparable to Google and Facebook.

To give people a sense of this, it is not unheard of for large scale bioinformatics platforms to set off alarms and/or zone-level capacity issues with the large cloud providers.

Re: Blood test that finds 50 types of cancer is accurate enough to be rolled out

#272

Post by deeviant »

rackjack wrote: post #190
fallingknife wrote: post #186

Earlier quoted context omitted.

> but doctors can't always predict this and aren't perfect decision making machines So mass screen healthy people, collect the data, run models, and get better at it. People like you would rather not try, and this is the same reaction I get from doctors. Applying the same tech that we use to improve ad targeting to disease prediction is a no brainer to anyone whose cushy job doesn't depend on the current medieval sta…

Same vibe as "I would just simply..." What do you think the entire medical, pharmaceutical, bioinformatic, etc. industries have been doing for decades? Are you really so arrogant to think that other people are too lazy and stupid to think of your brilliant idea and that you are simply more intelligent than everybody else? Do you really think people haven't been trying?

> Are you really so arrogant to think that other people are too lazy and stupid to think of your brilliant idea and that you are simply more intelligent than everybody else? Do you really think people haven't been trying?

I find it hard to believe I'm reading this sentiment on HN. Do you realize nearly any disruptive idea has do the "arrogant" thing you are speaking off.

Big companies go out of business all the time, industry disappear or wane all the time, big companies/industries with lots of smart people do stupid stuff on the regular. Characterizing the desire to do something other than status quo as "arrogance" is just the bottom of the barrel. I'm glad Semmelweis didn't think the way you do.

Re: Blood test that finds 50 types of cancer is accurate enough to be rolled out

#273

Post by theptip »

TaupeRanger wrote: post #96
reacharavindh wrote: post #3

This is one of those medical revolutions that I am waiting dearly for. Facilities that are not hospitals(to avoid the risk of occupying medical devices that sick people need) built to _regulary_ check up otherwise healthy people for preventive care. Heck, I have so many alerts defined on my monitoring setup for servers to watch for signals of failure before they get too big. But, my own body is not observed until som…

Actually you don't want this, and you are describing a nightmare scenario that everyone who studies health policy understands all too well. Mass screening of healthy people will result in extreme iatrogenics and unnecessary psychological damage and stress (which leads to physical effects as well), not to mention overwhelming the medical system. The fact is that many things that could be detected will never result in…

While I agree with the point that you're making around employing caution against iatrogenics (with colonoscopies being a very good case study that one should make sure to understand before forming an opinion here, as you referenced in another point), I think you're overconfident in your prediction that this hypothetical scenario would be bad.

I think your claim (based on sibling posts) is that in the current medical system, if we just added more screening, we'd not necessarily get net benefits. But I think that ignores the fact that, if we had cheap and high-resolution screening, we could fundamentally restructure many aspects of medical care. The BMJ article you linked in a sibling[1] notes that cancer screening may reduce cancer mortality but increase all-cause mortality. That's an unexpected and problematic result of getting referred to a cancer specialist that might not have (or be incentivized to care about) a wholistic picture of health when you screen positively for cancer. But if we had higher-resolution data, and conceptualized medicine as primarily preventive instead of curative, then it seems likely to me that overall mortality would be your target, we'd have richer data to be able to track that endpoint, and so we'd be more likely to catch the cases where an intervention caused unexpected harms (because we'd be tracking more indicators).

In other words, the problem you're observing is that adding a bit more data to the current system can produce negative outcomes. But that problem would be fixed by adding even more data. (With the remaining question being, how much data would we need to add to reach the "net positive" regime?)

I think you're arguing against a change that looks like a harm from the perspective of a local optimum that we're currently working towards, without considering the dramatic paradigm shift into another higher-utility region that would have been brought along by this sort of technology.

In summary, I am much more optimistic that if we had orders of magnitude more data, we'd make better decisions, not worse. But I agree with your caution that it's not as easy as it seems.

[1]: https://www.bmj.com/content/352/bmj.h6080

Re: Blood test that finds 50 types of cancer is accurate enough to be rolled out

#274

Post by jghn »

rackjack wrote: post #255
avion23 wrote: post #242

Earlier quoted context omitted.

> Are you really so arrogant to think that other people are too lazy and stupid to think of your brilliant idea and that you are simply more intelligent than everybody else? Not OP, but yes, I do. I've had some runins with the health system. At least the parts that I've seen are worse than the dark ages. Especially endocrinologists have absolutely no clue what they are doing. The ones I met don't even have superficia…

You're talking about praxis, we're talking about research. I agree the praxis can be pretty bad, but in regards to the above commenter's remarks on why people don't just simply collect data and apply it, medical professionals simply cannot try out new treatments the way they are suggesting.

To go further, a large issue/distraction in biomedical research has been Big Tech types coming in assuming that the roadblock all along has been lack of smart computational people in the process. I will not name names, but have seen so many instances of personal tech heroes coming in & claiming the underlying problem was that some of the brightest computational I've ever encountered simply didn't know how to computer.

Nothing could be further from the truth. People coming in to "disrupt" only add noise. Eventually those people either understand this and put the effort in to understand the domain or they wander off.

Re: Blood test that finds 50 types of cancer is accurate enough to be rolled out

#275

Post by burnished »

rackjack wrote: post #249
JumpCrisscross wrote: post #225

Earlier quoted context omitted.

> these cures are often brutal Heart disease is a huge deal. It ruins your life. (Maybe not in all caps.) Nevertheless, we regularly test for it, including with techniques with high rates of false positives. Few panic because almost everyone knows someone who got a false positive and didn't promptly keel over and die. If healthy adults are screened for cancer, there will be cultural memory of people who got a false p…

I don't enough about heart disease treatment to comment on the degree it ruins your life. People already get further testing. People already get second opinions. In the time you are changing your lifestyle (a good option for helping treatment, I agree) and increasing monitoring you could already be progressing beyond treatability. You can argue about whether it's alright to tell sub-1.5 million people each year who d…

Hey, I can see this is emotional for you, but have you considered a world in which it is not telling this vast body of people "you definitely have cancer"? Something more like "we detected XXppm of [marker] which indicates we might need to do some more testing, can we talk about [risk factors]?".

It just doesn't need to be as dire as what you are projecting.

Re: Blood test that finds 50 types of cancer is accurate enough to be rolled out

#276

Post by jghn »

fnord77 wrote: post #153
plank_time wrote: post #128

Earlier quoted context omitted.

Utterly wrong. You are conflating current technology like MRIs and CT scans that only detect lumps, to blood tests that detect CANCER. Yes, if every lump were treated and excised then it would be problematic. But CANCER is different. The only cancer that you might be able to leave alone is prostate because it grows so slowly. Everything else is a risk. And if we can treat cancer at early stage 1, then maybe people wo…

cells turn cancerous all the time and usually the body eliminates them without issue. this blood test is still going to hit all sorts of "false" positives, where it detects some cell that has gone cancerous that would have been eliminated anyway.

I'm far from expert but I don't think this would be a large concern. My understanding of CTCs (circulating tumor cells) is that they are shed by a growing tumor. A random weird cell doesn't seem likely to be turned up in a test like this. You need some amount of quantity to set off the proverbial alarm bells

Re: Blood test that finds 50 types of cancer is accurate enough to be rolled out

#277

Post by amelius »

AlexCoventry wrote: post #259
TaupeRanger wrote: post #96

Earlier quoted context omitted.

Actually you don't want this, and you are describing a nightmare scenario that everyone who studies health policy understands all too well. Mass screening of healthy people will result in extreme iatrogenics and unnecessary psychological damage and stress (which leads to physical effects as well), not to mention overwhelming the medical system. The fact is that many things that could be detected will never result in…

If we optimistically assume the claimed 0.5% false positive rate is accurate, and all of the US got tested annually, that's 1.64M false positives per year. Cancer.gov is telling me that approximately 1.8M USians were expected to get cancer last year. That's a positive predictive value of 52%. That still seems highly informative, to me; much higher than the PPV for mammography according to this (admittedly old) study:…

Isn't this exactly why the headline reads "blood test good enough to be rolled out"?

I.e., higher FP rate, and it wouldn't be rolled out.

Re: Blood test that finds 50 types of cancer is accurate enough to be rolled out

#278

Post by DoreenMichele »

reacharavindh wrote: post #3

This is one of those medical revolutions that I am waiting dearly for. Facilities that are not hospitals(to avoid the risk of occupying medical devices that sick people need) built to _regulary_ check up otherwise healthy people for preventive care. Heck, I have so many alerts defined on my monitoring setup for servers to watch for signals of failure before they get too big. But, my own body is not observed until som…

Why can’t we observe ourselves medically and analyze that record for early signs of trouble before it becomes serious?!

We can and plenty of people do, usually with tools like health journals and smart watches recording biometrics.

Re: Blood test that finds 50 types of cancer is accurate enough to be rolled out

#279

Post by jghn »

ggrrhh_ta wrote: post #253
dxyms wrote: post #134

Earlier quoted context omitted.

> If you get a positive with an uncertainty in its accuracy, at the very least, the test is repeated. But even more, you can use the information from the investigation of the reason for the false positive to improve the tests in the first place. This assumes that the false positive is caused randomly. That's not the case. False positive tests are usually followed by false positive tests. Then it will take years to fi…

That is very interesting. I assumed that false positives is generally a testing error (testing with another method or from another company would not lead to the same result). If the false positive is a result of a non-dangerous anomaly of the person being tested, then, I see how testing without symptoms can be worse.

Herein lies the real issue. Biology is a very, very messy science. So yes it could just be a testing error. But it might not be. It might be that something in your body behaves in a way that's unexpected. It might be some other non-dangerous anomaly as you cite.

We understand far more than we did say 20 years ago. But the problems are non-trivial on a scale most people don't appreciate.

Re: Blood test that finds 50 types of cancer is accurate enough to be rolled out

#280

Post by skybrian »

TaupeRanger wrote: post #133
throwawaynotmd wrote: post #109

Earlier quoted context omitted.

The argument you’re making has always bothered me because it’s hiding the ball. If finding something that otherwise carries no symptoms is best left untreated, then the fact that you found it should make no difference to the decision. The doctor should say that the best course of action is to do nothing. More information can never be harmful. If you know information is best not acted on in the abstract, then you also…

Lots of problematic assumptions in your reply. >If finding something that otherwise carries no symptoms is best left untreated, then the fact that you found it should make no difference to the decision. The doctor should say that the best course of action is to do nothing. More information can never be harmful. Absolutely and demonstratively false. There is an entire field of health policy that destroys this harmful…

I have no expertise here but I worry that these trials are studying the decision-making processes around how people decide to use the information from these tests, rather than the tests themselves.

How people use information varies, so the data might not have external validity - it’s culture specific, and cultures differ. Cultures can also change through accumulated experience.

So do the people studying these things try again with different and possibly better decision-making, or do they conclude that the test itself is no good?

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