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Comment by jacquesm | Hacker News Reader

Your belief has no representation in medical science, which is mostly evidence based. A lot of data has been collected on this, studies (many) have been conducted and the general consensus is that more testing absent symptoms does not lead to improved patient outcomes.

That you want to have some kind of theoretical argument in the face of this evidence might be interesting to you but it isn't to me.

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Less information is better?

That would be a bit of a paradox in science. I suppose we might take 2 steps forward and 1 step backward in the short term. As medical science advances, hopefully we can address any shortcomings from the additional early knowledge.

I noticed that pancreatic is on the list. This cancer is almost always fatal because we can't detect it early.

> Less information is better?

This really depends. Information that does not help make a good decision is just noise. It might seem like diagnostic information should always help make a good decision, but that isn’t always the case. If the false positive rate is higher than the base rate, a positive test would be more likely to be wrong than right, even with a very high accuracy.

https://en.wikipedia.org/wiki/Base_rate_fallacy

People are idiots that don't understand statistics. Telling them they tested positive is all they hear, and it leads to them making subpar decisions that often involve invasive surgery. Yes, it's paternalistic, but the fact is most people aren't informed enough to make medical decisions for themselves.

No, that's not the point. On an individual basis knowing for sure that a person who has symptoms has cancer, especially what kind of cancer, is a positive. On a population scale knowing that people without symptoms may have cancer with an 0.5% false positive rate and an 18-50% true positive rate is quite possibly a negative.

Less information can be better. Or more accurately, conditional probabilities can be better than unconditional probabilities.

For example, a large number of unnecessary antibiotic treatments, which fuel resistance, are triggered by doing diagnostic testing on patients with no symptoms.

"Diagnostic stewardship" is a concept that exists for a reason.

You’re making an unwarranted assumption: that the choice is between early detection with current responses to detected cancers and no early detection at all. Optimizing the response to an early detection will give a result no worse than either of those, since the choices of what to do include doing whatever doctors did in the studies that have poor results as well as doing nothing at all.

No, that is not the assumption. The assumption is that the only way in which such a test will be useful is by applying it absent symptoms to the population en-masse aka screening.

And that - no matter who good the test, and no matter how early - leads to a decrease in positive patient outcomes.

This is established medical science, and it pains me to have to continue to point out the same thing over and over again, but since I started with this response I feel obliged to continue to do so.

The outcome of a cancer treatment is not pre-determined, there are a lot of individual factors at play here that will have a huge effect on the outcome, possibly much larger than the effect of that particular cancer itself.

So en-masse screening leading to an increased number of treatments of pre-symptomatic cancers with those current responses is not a choice, we know that this will lead to a worse outcome across a population.

Early detection does not add anything to that. If you could pick out those individuals for which early detection would make a difference then that would be a gamechanger, and here the ball is currently in the genetics court.

The other part where major change can be made is by finding ways to treat cancers in a way that is non-invasive and does not put the patient further at risk (so no surgery, chemotherapy or radiation therapy).

And that - no matter who good the test, and no matter how early - leads to a decrease in positive patient outcomes.

You keep writing comments in absolute terms and talking about evidence, but how do you reconcile your position with the results of successful screening programmes like cervical smear testing? Detecting and treating high risk HPV before it causes changes that can turn into cervical cancer has dramatically reduced the harm caused by cervical cancer itself at a population level. Routine screening of this type isn't normally recommended for young women, but it becomes increasingly effective with age and screening programmes operate accordingly.

Yes, but that's one specific cancer. There are a few others for which this is the case and absent genetic data a few that are borderline cases (notably: breast cancer, where the presence or absence of a mutation is a very relevant bit of data).

So you do agree that evidence-based screening programmes can be effective then? In that case, I'm sorry but I don't quite understand the point you're trying to make here.

Yes, they can, but not in a blanket fashion where a test with a relatively high false positive rate and a relatively low sensitivity (between 18 and 50% for this particular test) is released without patient outcomes as the main driver of whether or not to apply the test absent further symptoms.

Whether this test is one that can serve in that particular role is definitely not something that has already been determined and those advocating for such are ignoring a mountain of established science and are simply jumping the gun.

Policy is set by the overall effect of application, which can be quite different than applying that same tool in an individual setting. This whole thread started with

"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."

And that is not something you do without taking into account the downsides. Whether this is revolutionary or not remains to be seen, it definitely is a useful test based on what I've read about it so far.

Well. With a bad test, what is necessary is to improve the test. The argument "outcomes are worse off with more absent symptoms testing" is really saying that symptoms is more predictive than the test itself: test is positive if [symptoms & positive result] test is positive or neutral if [no symptoms & should have been screened & positive result] and test is negative if [no symptoms & should not have been screened & positive result] (notice that this does not change the outcome to not testing people without symptoms and without another reason to do so). Until the tests/decision protocols were improved to avoid false positive, this third case should be communicated to the person as a negative result of the test (if we are convinced that the overall outcome is better off if the test should not have been administered at all), but I would find that unethical and dehumanizing and I understand touches on lots of ethical issues: the stress of waiting for a result, the liability of not being an actual false positive, etc. So, I understand, that given the current state of the testing, the decision is to restrict when to do it.

You are visibly making progress in your understanding of the problem, for which you are to be commended, especially if you are a complete layperson in this field. Thank you.

This test isn't a 'bad test', though applying it in the wrong way can lead to bad outcomes. This is why tests used absent symptoms have to have a false positive rate that is much lower than the base rate at which the disease occurs. These tests - unlike software tests - should not be thought about in absolute terms but in terms of probability, so a positive test indicates a probability that you have a specific disease, but it is very well possible that you do not have it, and a negative test indicates a probability that you do not have it - but it is very well possible that you in fact do have the disease. And the reasons for a false positive or false negative may have nothing to do with the test itself, but could easily be an environmental factor or some benign aspect of the test subject that was not accounted for when designing the test.

Whether or not a test is suitable for mass screening hinges on the factors above, the base rate for the disease, the age of the group being tested, in some cases gender and so on. In order to have a positive outcome across the population all these factors have to be taken into account and by the time that you have done so there are - unfortunately - at the moment no miracles to be had. But combinations of knowledge, for instance a genetic pre-disposition to a certain disease + a positive test can have much higher signal to noise ratios than either by themselves.

But make no mistake: this is an important development in medical diagnostics and it may very well be that once more evidence has been collected and some of the kinks have been worked out that this particular test or an improved version of it can be applied in a screening setting for one or more of the cancers that we currently have no reliable detection method for and that could be cured if detected early enough given a high enough base rate and a low enough false positive rate.

Note that the scientists behind the project are very careful with their statements and that the reporting on this was actually quite neutral and trends to cautious optimism, which I think is warranted, but until the result of the new studies is known it is way too early to shout 'revolution'.

Well, yes, it's only worth running a screening programme if you have a usefully accurate test and if you can then make some useful intervention after a positive result. Is anyone here disagreeing with that, though?

Maybe we interpreted OP's comment that you quoted differently? I read it as being in favour of preventative medicine as a whole, not necessarily endorsing this specific test at this specific point in time.

Maybe I'm also interpreting some of the other comments in this discussion, including yours, differently to how their authors intended them. My concern is that as written they appear to be criticising all use of screening, regardless of its efficacy, which is extremely dangerous.

That certainly isn't the goal, it is strictly meant within the context as established by the root comment. To present this at the present time as a revolutionary breakthrough and to suggest using this test in particular for mass screening is not a path that will lead to a good outcome unless a lot more data is gathered to support that position.

The people that have built this are at the forefront of this field, I've been following them for quite a while - since the announcement in March last year - it has direct bearing on some other things that I'm involved with and I'm hopeful that it will at first be a useful diagnostic tool and that in a later stage - after the kinks have been worked out and there is sufficient data - that it might help with more than that.

Preventative medicine obviously has its place and for selected cancers we are now in a phase where early detection leads to improved outcomes. But we should continue to be weary of overselling this - the same has already happened with other cancer tests.

Absent symptoms mass testing has serious risks and these will obviously be taken into account when setting policy, the article is actually reasonably neutral in this respect so I wonder why it leads to an immediate response that is equating this with a medical revolution. It may well be, but there is no evidence right now that this is the case.

You’re correct in that this is a prevailing view in epidemiological/Public Health circles. But Medical Science is not only the macro but also the micro level perspective. Individual Practitioners of medicine might well appreciate more and earlier Data. A first principals based argument is a complementary approach that might uncover things that an empirical view might hide.A good example of this is the Australian Noble Laureate Barry Marshall (https://www.discovermagazine.com/health/the-doctor-who-drank...). As long as the hypothesis can consequently be validated in controlled clinical studies, a theoretical argument even without existing foundation in empirical literature can still make for good science.

Absolutely, on an individual basis is where the difference can be made and this is exactly why it is important if you are tested positive for some cancer to work together with your oncologist to ensure the best possible outcome for you. The interesting thing here is that laypeople tend to be in favor of massive testing and almost always want to be operated on/have chemotherapy/have radiation therapy even if that is not necessarily the best path for them.

This leads to lots of suffering and hardship.

> A lot of data has been collected on this, studies (many) have been conducted and the general consensus is that more testing absent symptoms does not lead to improved patient outcomes.

Where can I find the studies that conclude this?

https://www.ncbi.nlm.nih.gov/books/NBK66205/

https://www.ncbi.nlm.nih.gov/books/NBK223933/

https://www.theguardian.com/society/2021/may/12/annual-scree...

Those are popular and accessible, the actual studies you can find through Google Scholar, SciHub or various medical publications.

This is not something where the general public - or software developers, who seem to treat cancer as a bug that needs to be fixed - are going to be very helpful, I am more than happy to trust the medical establishment with this.

What would be a game changer would be rather than improved testing something that would destroy tumors in-situ in a non-invasive manner that does not involve radiation or attempts to poison the body just this side of death.

Not just that, but neither GP nor anyone else in this thread seems to be mentioning the mental health implications of constantly screening for life threatening diseases. For me, and many others I am sure, this would be bad. My quality of life would suffer tremendously, to the point of likely substantial loss of mental function. And I am definitely not one of these “we all die someday” types. Far from it. It’s just that if you’re prone to anxiety, especially the hypochondriasis variety, the picture is much more complex than thinking of yourself as a server hooked up to monitoring.

> mental health implications of constantly screening for life threatening diseases

...to be contrasted with the mental health implication of living with the knowledge that you are *not* being tested and that cancer can grow undetected for years.

That, if anything, is a very good reason for anxiety.

Yes, that's a very important point. Even regular checks for cervical cancer or breast cancer can be a huge stress factor, especially in the period just prior to the test and in the waiting period until the results are in, and even more so if the test yields a false positive.

Is the problem not so much the testing, but that most current treatments for cancers are so crude? If you have a relatively asymptomatic cancer, the treatments (chemo, surgery, proton beams) and psychological stress of discovery could be worse (statistically) than letting the body naturally take care of it. This probably depends very much on the cancer ( e.g., some Thyroid cancers might be better left alone).

If our best treatment for fixing a harddrive was to hit it with a hammer, then maybe we'd also conclude monitoring for minor bit errors in data centers is unwise too.

Fair point: if we had a completely non-invasive cancer treatment then that would be a game changer (I made that some point in an earlier comment far down in the thread). And in that case it would lead to improved patient outcomes. But the current regime of tests+treatment options does not in the general case - and there are quite a few exceptions that mostly have to do with genetics - lead to improved outcomes.

Your point is interesting. Can you cite some literature that supports it?

Look up the term "iatrogenics" or check out oncologist Vinay Prasad's podcast called Plenary Session where he often talks about the dangers of over screening.

See below, there are quite literally 100's of studies supporting this so it should not be difficult to find many more articles about this.

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