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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

#361

Post by Jap2-0 »

captainmuon wrote: post #342
Fomite wrote: post #304

Earlier quoted context omitted.

"More information can never be harmful." In my particular field of biomedical research, there has recently been a push for "Diagnostic Stewardship" because more information has demonstrably been harmful to patient well-being.

I believe that's what the data says, but I have a really hard time reconciling it with common sense. More information is strictly better than less information, because you can always choose to ignore the extra information. I would say most medical decisions are made either due to statistics, or due to experience. What treatment has the highest chance of making the patient better, extending their life, or giving the b…

> you can always choose to ignore the extra information.

Can you?

That is to say: you can try, but I don't think most people are very good at consciously choosing not to think or worry about something that they know, if that's even possible.

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

#362

Post by ganafagol »

throwawaynotmd wrote: post #109
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…

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…

> More information can never be harmful.

That statement alone shows blatant ignorance of basic properties of the human psyche which makes reading the rest of your long reply rather pointless, as thought-through as it might have been from your perspective.

Humans are not the perfectly rational machines you seem to make them out to be. You need to deal with people in the real world, not some dream utopia that does not exist.

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

#363

Post by novok »

throwawaynotmd wrote: post #160
TaupeRanger wrote: post #133

Earlier quoted context omitted.

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…

> Many times the patient will push them for further tests and treatment (or the doctors will advocate for it to ease the mind of the patient) which leads to potential harm from unnecessary treatments. > People will ask to be treated anyway, and iatrogenics will rear its ugly head. I just want to say that you are in agreement with my position here. Your point about psychological problems is interesting, but as long as…

I think once you become a doctor, you quickly realize that a large amount of the population do not have the temperament to deal with 'maybe' bad news. Many are not the 135 IQ %1 of the population with a low anxiety personality who accept that they will eventually grow old and die, which happens to coincide with many engineering types on HN.

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

#364

Post by moralestapia »

timy2shoes wrote: post #355
scarecrowboat wrote: post #331

Earlier quoted context omitted.

What if the followup procedure is invasive and expensive? It's possible that this procedure could be net negative in aggregate depending on the % of false positives and # of resulting needless followup procedures. Not to mention the emotional stress.

Exactly! This reminds of the recent case of the AMA increasing the suggested age of regular mammograms. More testing means earlier detection of breast cancer. But a false positive means an invasive biopsy. These are the two sides that need to be balanced. The AMA decided that since the base rate of cancer is so low in women under 50, the posterior probability that you have cancer given a positive mammogram for the un…

>But a false positive means an invasive biopsy.

Nah, there's plenty of other things you'd try before the biopsy.

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

#365

Post by moralestapia »

scarecrowboat wrote: post #331
moralestapia wrote: post #293

Earlier quoted context omitted.

I feel it's a net win anyway, if the procedure is not invasive and cheap, you could take one every so often (yearly?) and if something shows up you just double check with a better method or w/e. Better than nothing, which is the current alternative.

What if the followup procedure is invasive and expensive? It's possible that this procedure could be net negative in aggregate depending on the % of false positives and # of resulting needless followup procedures. Not to mention the emotional stress.

Don't do it, then. Try homeopathy or whatever thing feels good for you.

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

#367

Post by dan-robertson »

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:…

Is that actually good though? It feels to me that there’s a big difference between explaining the implications of a positive result to someone who understands bayes theorem and someone who doesn’t.

Another aspect of cancer screening is that detecting cancer earlier can improve key statistics like 5 year survival without affecting the actual disease in any way. Which can make screening sound more effective than it is.

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

#368

Post by pie420 »

novok wrote: post #363
throwawaynotmd wrote: post #160

Earlier quoted context omitted.

> Many times the patient will push them for further tests and treatment (or the doctors will advocate for it to ease the mind of the patient) which leads to potential harm from unnecessary treatments. > People will ask to be treated anyway, and iatrogenics will rear its ugly head. I just want to say that you are in agreement with my position here. Your point about psychological problems is interesting, but as long as…

I think once you become a doctor, you quickly realize that a large amount of the population do not have the temperament to deal with 'maybe' bad news. Many are not the 135 IQ %1 of the population with a low anxiety personality who accept that they will eventually grow old and die, which happens to coincide with many engineering types on HN.

Lol, i would argue that engineers, many of whose primary job function is to imagine worst case scenarios and engineer around those to prevent accidents, data loss, etc. Are the exact type of people that are prone to hypochondria. It's not about growing old and dying, it's about ignoring a stomach ache for a couple months and then being told you have terminal cancer, and then living with the regret of "if only I got it checked out earlier".

In the engineering world, you are almost always rewarded for being extra safe and testing, fixing, and investigating anything that might seem a little off. If you do blood tests, MRIs, and cancer screens for every mole, cough, and stomach pain, you will go insane and develop hypochondria.

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

#369

Post by Fomite »

captainmuon wrote: post #342
Fomite wrote: post #304

Earlier quoted context omitted.

"More information can never be harmful." In my particular field of biomedical research, there has recently been a push for "Diagnostic Stewardship" because more information has demonstrably been harmful to patient well-being.

I believe that's what the data says, but I have a really hard time reconciling it with common sense. More information is strictly better than less information, because you can always choose to ignore the extra information. I would say most medical decisions are made either due to statistics, or due to experience. What treatment has the highest chance of making the patient better, extending their life, or giving the b…

"I believe that's what the data says, but I have a really hard time reconciling it with common sense."

Can you see why some people might be hesitant about basing medical treatment on "That's what the data says, but it doesn't conform to my priors, so it's probably wrong"?

People are terrible at ignoring information. Clinicians are people. We know this.

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

#370

Post by novok »

pie420 wrote: post #368
novok wrote: post #363

Earlier quoted context omitted.

I think once you become a doctor, you quickly realize that a large amount of the population do not have the temperament to deal with 'maybe' bad news. Many are not the 135 IQ %1 of the population with a low anxiety personality who accept that they will eventually grow old and die, which happens to coincide with many engineering types on HN.

Lol, i would argue that engineers, many of whose primary job function is to imagine worst case scenarios and engineer around those to prevent accidents, data loss, etc. Are the exact type of people that are prone to hypochondria. It's not about growing old and dying, it's about ignoring a stomach ache for a couple months and then being told you have terminal cancer, and then living with the regret of "if only I got i…

I guess depends on the mental counter response those engineers take. Because you have to think about every possibility, you create a counter temperment that doesn't implode thinking about every possibility.

Some might go the other way, and their anxious personality might help them think about everything, but also make them a stress case.

I think the first type tends to last longer in the industry, at least for my coworkers.

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