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 find out if it was a false positive or not.
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.
You can't just repeat the test, that is generally not where the problem lies. You'll get a second positive result and still don't know if it's a false positive or not.
And in many cases there aren't other non-invasive test you can perform. If you can't actually determine reliably if some anomaly will cause trouble before removing it, whole population screening will cause unnecessary operations.
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.
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.
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.
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.
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).
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.
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.
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'.
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.
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.
This leads to lots of suffering and hardship.
Where can I find the studies that conclude this?
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.
...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.
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.
A positive blood test is a symptom. One which you'll miss if you don't do the blood test regularly.
And looking for symptoms (other than a blood test) is a form of testing... one with much worse accuracy (both positive and negative) than the blood test, especially in the early stages.
https://www.cancer.gov/publications/dictionaries/cancer-term...
"A physical or mental problem that a person experiences that may indicate a disease or condition. Symptoms cannot be seen and do not show up on medical tests. Some examples of symptoms are headache, fatigue, nausea, and pain."
It is not a good argument. In fact, it makes no sense. 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. If we weren't humans and the uncertainty of the test is known then at the very very very least you could throw a dice to decide whether you discard or not the test result.
If more information leads to worse decisions it just means that the noise level introduced by the test is just too high. A way to reduce the noise is two amplify the signal, and a way to amplify the signal is to look for more information (other tests, other indirect measurements: i.e., look for B if A was positive, etc.).