
Scientists develop 10-minute universal cancer test - charlysl
https://www.theguardian.com/science/2018/dec/04/scientists-develop-10-minute-universal-cancer-test
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melling
“The test has a sensitivity of about 90%, meaning it would detect about 90 in
100 cases of cancer, with 10% false positives.”

That’s a large error rate.

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x1798DE
It's particularly bad because the baseline rate for cancer is pretty low. The
incidence rate for men and women in the US from [1] is 439 per 100k. So taking
into account the baseline rate:

Of 439 people with new cancers, 395 (90%) will get a positive result. Of
99,561 people without cancer, 9,956 (10%) will get a positive result.

So a total of 10,351 people will get positive results, and 96% of those people
will not have cancer, so a positive result means that you have (to a first
approximation) a 4% chance of having cancer. If the breakdown from [2] is
roughly accurate, taking into account no other risk factors, someone under 50
can expect an even _lower_ baseline rate, the "true positive" rate of a test
with 90% sensitivity would range from 0.1% in infants to 25% in people 90+
years of age.

1\. [https://www.cancer.gov/about-
cancer/understanding/statistics](https://www.cancer.gov/about-
cancer/understanding/statistics)

2\. [https://www.cancerresearchuk.org/health-
professional/cancer-...](https://www.cancerresearchuk.org/health-
professional/cancer-statistics/incidence/age#heading-Zero)

~~~
cuchoi
That's a great point but I imagine doctors won't start running this test in a
random sample of the population. They would probably run it in people with
symptoms --> makes them a lot more likely to have cancer.

