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

#201

Post by jacquesm » Fri, Jun 25, 2021, 3:02 PM UTC

ssijak wrote: post #94

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…

The test in the article actually has very few false positives. And who knows, maybe even those false positives were just extremely early cases of cancer.

Very few false positives: 0.5% false positive rate times 1,000,000 people screened translates into 5,000 false positives, which is in absolute terms not a small number. Those will take away resources from symptomatic patients.

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

#202

Post by phunehehe0 » Fri, Jun 25, 2021, 3:03 PM UTC

starkd wrote: post #194

"It correctly identified when cancer was present in 51.5% of cases, across all stages of the disease, and wrongly detected cancer in only 0.5% of cases." Doesn't this seem kind of low? Just a bit better than a coin flip. Of course, it rises to 65% and 87% for certain circumstances and the false positive rate is low, but it seems like a lot of cancers could fail to be detected and give a false assurance patients are c…

This is much better than a coin flip. A coin flip would give about 50% true positive rate (which is about the same as the test), but it would also give about 50% false positive rate.

To put it in perspective, imagine 10 people have cancer in a population of 1000 (a rate of 10% which is too high compared to what I think the real number should be). The test would fail to identify 5 of the people with cancer, and it would say that 5 of the people without cancer have cancer. So overall it would misidentify 10 people. The coin flip would misidentify 500 people.

Amusingly in this example if you have a "test" that just says nobody has cancer it would also misidentify only 10 people :) I think this is why they are reporting true positive rate and false positive rate.

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

#203

Post by jcims » Fri, Jun 25, 2021, 3:04 PM UTC

TaupeRanger wrote: post #138

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…

You say "utterly wrong" and yet you clearly have no idea what you're talking about and have never even approached the field of health policy. Screening has to PROVE that it makes people live longer or better, just like any other intervention. It is not the case that screening is automatically good, otherwise we would be giving 20 year olds colonoscopies. Just because you find something, doesn't mean you've helped the…

Your replies to folks in this thread contain the same hubris as the content of your message, which in turn is consistent with the hubris I've encountered in the medical community over the past five years.

My wife went to urgent care twice in three months because of a pain in her side. She was turned away with cough medicine. She finally went to the ER where a CT scan revealed massive tumors in her abdomen that had gone undetected for likely years. Genetic and semi-annual CA125 screening could yield quite a few false positives, but combined with her physical symptoms she may have had more cause to press at an incomplete conclusion and possibly could have had a different outcome. She underwent nearly $2M in medical procedures over the course of 26 months and died at 45 years old last year.

A few years prior to that I was spring cleaning one day and found a glucose test kit at the house. I had the whole family test their blood glucose. My youngest was 240mg/dL. We waited a day and tested again, same thing. We took her into the hospital and they actually admitted her for two days because they had no idea what to do with a child presenting with Type 1 diabetes that hadn't gone into full DKA. That's harmful, gross, and embarrassing. And this is a major children's hospital that was recently in the top ten in the nation for endocrinology.

In both of these situations, preventative screening could have or did have positive outcomes. I don't disagree with the effect that has been observed, but the conclusion being drawn from it is revolting to me. People should be permitted to make their own decisions about their level of knowledge of the state of their body. We only get one trip as far as we know, and I just find it unacceptable that people are willing to categorically deny diagnostic technology or bemoan its development because they they don't know how to support people trying to navigate the information it brings.

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

#204

Post by jacquesm » Fri, Jun 25, 2021, 3:09 PM UTC

Silhouette wrote: post #198

jacquesm wrote: post #192

Earlier quoted context omitted.

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.

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

#205

Post by rackjack » Fri, Jun 25, 2021, 3:10 PM UTC

So many tech people here thinking they know how the entire medical industry works... medical problems and the research that arises from them are staggeringly complex and messy. Please... if you've never had experience with this kind of thing, don't pretend that you do. Some uninformed person might see your comment and think you actually know something.

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

#206

Post by RGamma » Fri, Jun 25, 2021, 3:11 PM UTC

Clampower wrote: post #10

zrail wrote: post #5

Earlier quoted context omitted.

That's already a thing, at least everywhere I've ever lived. You have a primary care doctor, you see them at least once a year, they do a physical exam, maybe some blood work. This test maybe becomes standard of care for everyone annually.

This is not true in the Netherlands. You don’t get any tests if there is nothing wrong. Healthcare in this country scares me.

FWIW there's self-service blood tests with capillary blood at e.g. medivere.

Tried to do the cholesterol one, but couldn't get the blood into the tube shrug

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

#207

Post by jacquesm » Fri, Jun 25, 2021, 3:13 PM UTC

iandanforth wrote: post #200

jacquesm wrote: post #80

Earlier quoted context omitted.

The problem is not my mindset, but your understanding of the subject material. Patient outcomes have very little to do with the quality of the tests, even a 100% accurate test would not necessarily lead to improved patient outcomes because these are defined independent of the tests. You are treating this like a software problem, but it isn't, it's a medical problem, and medical problems tend to be complex because the…

You don't know what you're talking about. Before my software career I spent a few years working in a diagnostic medical field. Specifically osteoporosis testing. I worked both in a research capacity at Stanford looking at osteoporosis in older men (not pretending to be the PI here) and in a day to day testing clinic. So I've seen exactly what happens when you test a cross-sectional asymptomatic sample of the populous…

Sure, but that's a completely different setting than the one the OP described: mass testing for presence of cancers by non-specialist labs. And that's the thing that triggered my response. The outcome of such an approach could easily be a negative one.

FWIW I too have some experience with medical diagnostic systems (specifically: cancer testing), and one of the main reasons why I'm still skeptical about this test is that for many cancer types tested for the base rate is much lower than the false positive rate.

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

#208

Post by JumpCrisscross » Fri, Jun 25, 2021, 3:17 PM UTC

rackjack wrote: post #184

plank_time wrote: post #147

Earlier quoted context omitted.

We don’t give colonoscopies to 20 years olds because it’s an expensive, invasive test with a low rate of cancer. We don’t give mammograms to under 40 year olds these days because the same and it’s notoriously inaccurate. We give blood glucose level tests and cholesterol tests to everyone every year at the physical because they are cheap and easy to administer. Even though the effects of both may take decades to have…

> It correctly identified when cancer was present in 51.5% of cases, across all stages of the disease, and wrongly detected cancer in only 0.5% of cases. If all 300 million Americans get blood tested each year, that is 1 and a half MILLION people who are falsely told they have CANCER. One and a half MILLION people whose life gets turned upside down, WRONGLY, due to a blood test -- at least, until they take a second o…

> One and a half MILLION people whose life gets turned upside down, WRONGLY, due to a blood test

Culture adapts. Getting a cancer diagnosis today is a huge deal because testing is infrequent, usually in response to a problem, and the diagnosis tends to be late and accurate. If 1.5mm healthy people get a false positive every year, the general response will be stress until a second test confirms a false positive.

The lack of public trust in health policy doctrine, and the support for start-ups that can operate outside those channels, comes in large part from this type of thinking.

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

#209

Post by plank_time » Fri, Jun 25, 2021, 3:19 PM UTC

jcims wrote: post #203

TaupeRanger wrote: post #138

Earlier quoted context omitted.

You say "utterly wrong" and yet you clearly have no idea what you're talking about and have never even approached the field of health policy. Screening has to PROVE that it makes people live longer or better, just like any other intervention. It is not the case that screening is automatically good, otherwise we would be giving 20 year olds colonoscopies. Just because you find something, doesn't mean you've helped the…

Your replies to folks in this thread contain the same hubris as the content of your message, which in turn is consistent with the hubris I've encountered in the medical community over the past five years. My wife went to urgent care twice in three months because of a pain in her side. She was turned away with cough medicine. She finally went to the ER where a CT scan revealed massive tumors in her abdomen that had go…

Exactly. Also my sincerest condolences to you and your family.

The level of arrogance in these responses parroting what they’ve read in a paragraph online approaches that with what we saw early in the pandemic with masks.

“Masks don’t work! Fauci said so!” And the level of confidence they said it was shocking along with the self-righteousness.

Yes, maybe people can’t put on N95 masks properly... but maybe we can teach them? Is that so mind blowing? We teach people how to wash hands for 20 seconds, is it not so hard to believe you can’t teach people to wear masks properly? Maybe make masks that are easier to put on?

It’s sad how people with no vision are Karen’ing people to not think ahead or think of the future. It’s scary that it’s happening on hacker news.

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

#210

Post by treeman79 » Fri, Jun 25, 2021, 3:20 PM UTC

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…

I had a mystery illness. Spent hundreds of thousands on Er visits only to find it’s was a pair of fairly common conditions acting together. Blood work tests exists for both.

A deep round of blood testing would have saved everyone a lot of time and money and suffering.

Or I could have waited many years until the organ damage was so extensive that diagnosing was easier. Oh wait, that’s what ended up happening.