Blood test that finds 50 types of cancer is accurate enough to be rolled out • Hacker News Board

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

#51

Post by tarsinge » Fri, Jun 25, 2021, 12:05 PM UTC

jacquesm wrote: post #46

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…

Regularly checking people that are otherwise healthy for cancer will turn up a lot of cancer through false positives or slowly growing ones, will lead to a lot of unnecessary intervention and will in fact lead to a reduction in quality of life and lifespan. This is one of the reasons why exhaustive cancer screening (which was more costly in the past but could have been done) was not promoted, it had nothing to do wit…

> Those cancers where checkups are useful we already do regular screenings for.

More like “are and useful”.

Regarding your last paragraph cancer screening seems very rare except for one or two types (at least where I live), so statistically yes an annual test will miss the worst case you presented, but for the vast majority it will be a huge improvement.

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

#52

Post by konschubert » Fri, Jun 25, 2021, 12:09 PM UTC

thebelal wrote: post #33

konschubert wrote: post #17

If you’re tested positive, what’s the probably that you actually have cancer? (The article states 0.5% false positive rate and about 50% true positive rate, but I would need to know the the prevalence of cancer in the population to compute what I am asking for).

One of the cancers they mention is pancreatic cancer. A quick Google search suggests the prevalence of pancreatic cancer in the population is 13 per 100,000. So if you gave this test with a 0.005 false positive rate and 0.5 true positive rate to 100,000 people it would miss diagnose 500 people and only correctly detect 7 cancers. So given you had a positive test result there would be a 1-(7/500)=98.6% chance you did…

The false positive rate of 0.5% refers to the chance that there is ANY false positive in the whole screening, not just a false positive on the pancreatic cancer segment.

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

#53

Post by ggrrhh_ta » Fri, Jun 25, 2021, 12:09 PM UTC

jacquesm wrote: post #46

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…

Regularly checking people that are otherwise healthy for cancer will turn up a lot of cancer through false positives or slowly growing ones, will lead to a lot of unnecessary intervention and will in fact lead to a reduction in quality of life and lifespan. This is one of the reasons why exhaustive cancer screening (which was more costly in the past but could have been done) was not promoted, it had nothing to do wit…

Have heard your argument on the false positives and unnecessary interventions many times.

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.).

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

#54

Post by someguydave » Fri, Jun 25, 2021, 12:11 PM UTC

refurb wrote: post #44

sbelskie wrote: post #11

Earlier quoted context omitted.

A big part of this is the fact that learning information (about a disease or condition) early is often NOT the same thing as learning information that will change a patient’s clinical outcome.

Yup. Let’s say the test shows “very likely” for pancreatic cancer. Now you do imaging. Ok, nothing there? Now what? Biopsy? That’s general anesthesia now and costly (for the patient or govt). Biopsy is negative. Now what? Start chemo? Watch and wait? For how long? Do a biopsy every 6 months? None of these tests are 100% accurate. If broadly used, a false positive of 0.1% will result in tens of thousands getting unnec…

exactly, this screening is an invitation for overtreatment.

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

#55

Post by ggrrhh_ta » Fri, Jun 25, 2021, 12:14 PM UTC

ggrrhh_ta wrote: post #53

jacquesm wrote: post #46

Earlier quoted context omitted.

Regularly checking people that are otherwise healthy for cancer will turn up a lot of cancer through false positives or slowly growing ones, will lead to a lot of unnecessary intervention and will in fact lead to a reduction in quality of life and lifespan. This is one of the reasons why exhaustive cancer screening (which was more costly in the past but could have been done) was not promoted, it had nothing to do wit…

Have heard your argument on the false positives and unnecessary interventions many times. 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 un…

BTW... years ago I was rather supportive (albeit not having voiced it) of the argument that false positives lead to unnecessary interventions and thus screening should be itself gated.

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

#56

Post by jacquesm » Fri, Jun 25, 2021, 12:14 PM UTC

ggrrhh_ta wrote: post #53

jacquesm wrote: post #46

Earlier quoted context omitted.

Regularly checking people that are otherwise healthy for cancer will turn up a lot of cancer through false positives or slowly growing ones, will lead to a lot of unnecessary intervention and will in fact lead to a reduction in quality of life and lifespan. This is one of the reasons why exhaustive cancer screening (which was more costly in the past but could have been done) was not promoted, it had nothing to do wit…

Have heard your argument on the false positives and unnecessary interventions many times. 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 un…

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.

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

#57

Post by kokey » Fri, Jun 25, 2021, 12:16 PM UTC

refurb wrote: post #44

sbelskie wrote: post #11

Earlier quoted context omitted.

A big part of this is the fact that learning information (about a disease or condition) early is often NOT the same thing as learning information that will change a patient’s clinical outcome.

Yup. Let’s say the test shows “very likely” for pancreatic cancer. Now you do imaging. Ok, nothing there? Now what? Biopsy? That’s general anesthesia now and costly (for the patient or govt). Biopsy is negative. Now what? Start chemo? Watch and wait? For how long? Do a biopsy every 6 months? None of these tests are 100% accurate. If broadly used, a false positive of 0.1% will result in tens of thousands getting unnec…

I think for pancreatic cancer early detection just means it gives you more time to enjoy a slightly longer bucket list. For bowel cancers however, this could potentially buy many extra years since it's currently difficult to detect early.

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

#58

Post by jacquesm » Fri, Jun 25, 2021, 12:16 PM UTC

bruce343434 wrote: post #50

jacquesm wrote: post #46

Earlier quoted context omitted.

Regularly checking people that are otherwise healthy for cancer will turn up a lot of cancer through false positives or slowly growing ones, will lead to a lot of unnecessary intervention and will in fact lead to a reduction in quality of life and lifespan. This is one of the reasons why exhaustive cancer screening (which was more costly in the past but could have been done) was not promoted, it had nothing to do wit…

Who are "we"? I'm certainly not "regularly" screened.

That's your choice, assuming you live in a developed country.

Assuming the United States see here:

https://www.cdc.gov/cancer/dcpc/prevention/screening.htm

and if elsewhere consult your local CDC equivalent.

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

#59

Post by jacquesm » Fri, Jun 25, 2021, 12:19 PM UTC

ggrrhh_ta wrote: post #55

ggrrhh_ta wrote: post #53

Earlier quoted context omitted.

Have heard your argument on the false positives and unnecessary interventions many times. 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 un…

BTW... years ago I was rather supportive (albeit not having voiced it) of the argument that false positives lead to unnecessary interventions and thus screening should be itself gated.

Your understanding as evinced by the comment above leaves me to wonder if you actually get that this is not about individual outcomes but about the overall statistics. Even if more accurate tests would turn up more true positives that still would not necessarily result in increased patient outcomes. That is why absent symptoms testing makes sense for only a very low number of cancers where early detection does improve patient outcomes significantly, typically this is vastly improved if there is knowledge about the genetical make-up of the individuals.

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

#60

Post by dmitryminkovsky » Fri, Jun 25, 2021, 12:20 PM UTC

jacquesm wrote: post #56

ggrrhh_ta wrote: post #53

Earlier quoted context omitted.

Have heard your argument on the false positives and unnecessary interventions many times. 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 un…

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.

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.