A Device Could Detect Dozens of Cancers with a Single Blood Test (opens in new tab)

No, no, no. This is a perfect example of why everyone should be required to learn statistics.

We don't need a device to do multiple simultaneous screenings. If this were important, we'd already be doing multiple manual screenings and there would already be a demand for simplifying it. But there's a very good reason we do not do mass screening for cancers and other serious diseases with low incidence, no risk of transmission, and invasive treatment regimens.

Medical tests are not crystal balls. Any test you perform has a risk of false positives and a risk of false negatives, and even if you have a test with good specificity and sensitivity, applying any test to any large population with a low incidence of disease guarantees that most of the positive findings will be wrong.[1]

Telling hundreds of thousands of healthy people that they have cancer and sending them through intensive workup and/or treatment when they actually do not is emotionally and financially harmful to them and the broader community.

This is why we do not do population-wide CT screening for lung cancer, why we no longer stress that young women without other risk factors have mammograms (but can choose to if they are risk averse and are okay with potentially receiving unnecessary treatment), why we are moving away from aggressive PSA screening, etc.

What's the alternative? Targeted screening. If you reduce the size of people you screen to those most likely to be affected, then you dramatically improve your results. So people with symptoms (obviously), people with certain exposures (asbestos), genetic predispositions to certain types of cancers (BRCA), etc. In other words, the thing that works best is what we already do.

[1]: http://en.wikipedia.org/wiki/Sensitivity_and_specificity#Wor...

Aren't we all having some cancers cells in our blood and lymphatic fluids, and tissues, but those with a healthy immune response have nothing to worry about? In most cases, doesn't cancer take years to fully developed helped by epigenetic factors, but predominantly by the external ones? Won't such device when massively used for blood testing lead to predominantly false positives, redundant biopsies, and overtreatment? I think this is a great device with an enormous potential if used on narrow targets and responsibly, in general. I just think focus should be on true prevention, i.e. dietary and lifestyle changes, and not developing a false sense of assurance by living unhealthily and relying on a test to catch the results of the poor habits, and also rely on medicine being advanced enough to correct our mistakes. Of course, some factors are unavoidable today, but we also have a growing arsenal of knowledge and means to counter many of them.