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by idopmstuff 1022 days ago
> Given that screening is arguably benign for most people

You're 100% wrong here, this is not a given. Prostate cancer screenings, which are very common, can have both false positives as well as findings of cancer that is and would remain completely benign. These can both lead to unnecessary treatments that cause serious negative health effects, including incontinence and erectile dysfunction.

https://www.cdc.gov/cancer/prostate/basic_info/benefits-harm...

3 comments

Also read that death rates from thyroid cancer hasn't changed in 50 years. Despite huge numbers of thyroid screenings and treatment.

An ultrasound of the thyroid often leads to finding a nodule. Which leads to a biopsy. Which comes out indeterminate. Which leads to a thyroidectomy and life long dependence on thyroid hormones.

Another one is ductal carcinoma in situ. Read somewhere there is a 1% chance that will evolve into cancer. And yet you have women having double mastectomies and chemo for it.

Absolutely no one is getting a bilateral mastectomy or chemotherapy for DCIS.

This is by far the most inaccurate medical claim I've ever seen on HN. Where on earth did you get this from?

The whole point of diagnosing DCIS on screening mammography is that it avoids systemic therapy and mastectomy. It also wouldn't be bilateral.

Yes, they do. I have a friend who did just that. Was it justified? I don't know, but it's very real.
So work the numbers. Put together the chance of false positives, false negatives, rate of negative effects from treatment, and rate of death with and without treatment. Tell the patient the risk of each outcome.

The math is easy. If we don't have the numbers for it, then get them. Plenty of people get prostate cancer and some of them choose to just monitor. We should have plenty of information to make a rational decision. This seems preferable to blinding ourselves out of fear that we'll do something stupid with the information we might get.

> Tell the patient the risk of each outcome.

This isn't a simple problem of calculating EV. Telling somebody that there's a 40% chance that the positive test is actually wrong and in the 60% case that it's right, 40% of the time it's going to be benign, but if it's not benign it might kill them but if it is benign and they do surgery they might be left wearing diapers is not a simple thing for a person to evaluate. Add to that the fact that people have a bias towards action, so doctors tend to overindex on treatment vs. just ignoring something, and you have an incredibly complex problem.

> The math is easy.

No, it's not. It's a series of probabilities combined with extremely subjective outcomes (getting erectile dysfunction may have a very different impact on your life if you're 40 vs. 80).

> If we don't have the numbers for it, then get them.

You're just trivializing medicine and medical research here. Why don't you just go ahead and build some AI that'll solve this whole problem by diagnosing cancers based on a blood sample? That seems easy enough.

> This seems preferable to blinding ourselves out of fear that we'll do something stupid with the information we might get.

Ironically what you're describing here is the opposite of everything you've just talked about. If we understand the numbers well, and from those we can conclude that tests are highly prone to false positives and thus that treatment based on positive results is more likely to be harmful than helpful, then we shouldn't take those tests. That's not blinding ourselves, it's acting appropriately based on understanding the math.

No, I mean you take the test and if it's positive then present options like this:

Risk of death: X% with treatment, Y% without treatment.

Risk of side effect A: X% with treatment, Y% without treatment.

Those numbers take into account the rate of false positives and false negatives. They are clear and understandable.

There are definitely situations in which you shouldn't test: where the rate of the cancer is low, the false positive rate is high, and the risk of treatment is high. In that case, the numbers can show that risk of death is higher with treatment than without, so while (noninvasive) testing doesn't make things worse if we're giving clear numbers, it doesn't help either; we might as well not test at all. But that's not true for everything. As for side effects, we should give patients clear numbers like this so they can make informed decisions.

Adding up the number of false positives and negatives, and the number of patients with various outcomes, is not comparable to using AI.

You are also presented with a choice: you take a test and you die in X% because of the test itself (there are no non-invasive tests, even IV is potentially dangerous), or you may be diagnosed with cancer with Y% chance of right diagnosis and Z% of lethality. Math is getting much more complicated. Now consider that only 2.5% women will die from breast cancer, but 97.5% others will get X-ray exposure once a year (with 100% test coverage of course). X-rays are know to cause mutations and thus cancer. Add to this money spent on tests that can be used to find a cure (we don't have unlimited resources).
Simply having the information that they maybe have cancer, people are not great at just living unstressed because it may or may not be a false positive. And stress is known to cause a lot of problems including weakening immune system.
Which is why you only test in situations where, if the test is positive, you have better odds if you treat.
Better odds to live longer or have good life? Looks like this study says it's definitely not the former?
It’s important to note that it’s not the screening causing those issues. It’s the fact that our health care systems are rather inadequate in properly handling those screening results at the margin.