Comment by RobotToaster
6 days ago
>One study in 2020 found that 95% of asymptomatic patients had some type of "abnormal" finding, but just 1.8% of these findings were indeed cancer.
That can also be reframed as 1.71% of asymptomatic people having cancer, which is a really good argument for better screening.
The argument for better screening would require that finding those asymptomatic cancers actually improves survival rates. There are several reasonable scenarios where early screening doesn't improve it:
* The cancer is aggressive and resistant to treatment. Chemo/radiation only pause the growth for a bit, but ultimately the cancer keeps growing and the total survival time is the same (only that the patient spent more time knowing they had cancer).
* The cancer is susceptible enough to treatment that it's still curable when it becomes symptomatic and found through other means.
* The cancer is slow enough that the patient dies from other causes before.
Early screening brings benefits only when the cancer ends up causing issues and responds differently to treatment between the "early screening detection" time and the "normal detection" time.
It's impossible to know beforehand which of the scenarios have more weight, specially because we have very little data on what happens way before cancer is detected via the usual methods. We need better studies on this, and for now the evidence doesn't really point out to these large, indiscriminate screenings being actually helpful.
That’s not the correct framing - your assertion first lacks evidence about why we should screen better. In fact, we aren’t improving longevity in many early diagnoses, and may be treating people whose immune system would resolve the cancers.
Further, the denominator is asymptomatic people who were able to get MRI’s they didn’t need. That doesn’t tell us anything about the normal world.
> we aren’t improving longevity in many early diagnoses, and may be treating people whose immune system would resolve the cancers.
Even assuming your statement is true, if what is detected is small enough for that there's no reason "treatment" can't just be monitoring it's size with follow-up scans.
> Even assuming your statement is true,
It is true. You need only trouble yourself to search. Here's a recent paper, for example: https://jamanetwork.com/journals/jamainternalmedicine/articl...
> if what is detected is small enough for that there's no reason "treatment" can't just be monitoring it's size with follow-up scans.
This is false—it is exactly what the article is trying to convey. There is a risk to any test, and one of the major risks for imaging is getting treatment for things that would never cause symptoms or require intervention.
If the cancer is vizible in MRI or CT scans, the immune system already failed to "resolve" it and will not do so in the future, at least not without external help.
> If the cancer is vizible in MRI or CT scans, the immune system already failed to "resolve" it and will not do so in the future, at least not without external help.
This is false. A simple google search for spontaneous remission (or honestly anything similar) would show/have shown you this.
I wonder how biased the group is though, is the sample truly representative of the general population or is it a group of people who are already undergoing screen for some other health-related reason?