Move over, weight loss drugs. The next explosion in costs could be cancer detection tests.
Several new tests for cancer are now on the market. Galleri was first on the market, Cologuard has just introduced Cancerguard. Not to be outdone, an outfit called Mito screens for not just cancers, but 800 different conditions/diseases with a single blood draw.
Early detection is great, isn’t it? It will save money down the road, so shouldn’t we cover it? Before you decide to do so, consider these six (count ‘em, six) points that the Validation Institute would argue go exactly the other way:
- The test itself costs more than any other screening test except colonoscopies (which no longer have to be done, as noted in this webinar)
- What is someone supposed to do when this test “detects microscopic changes within your body” other than fret, go to the doctor, and get a biopsy for a cancer that doesn’t exist yet?
- Some of these biopsies (most of them, actually) are themselves invasive, expensive, and hazardous regarding complications.
- Biopsies for very nascent cancers are themselves shockingly inaccurate. You can easily take a bunch of samples from a thyroid, prostate, lung etc. that don’t show cancer but the cancer is elsewhere…and now you have to recover from the biopsy itself
- False positives. These tests are quite accurate, but you can be quite accurate and still have a zillion false positives. Suppose you have a 1-in-10,000 chance of a specific cancer, and a test is 99% accurate. It will very likely spot the person with nascent cancer. But 99% accurate means 1% in So 1% of those 10,000 – 100 people – will be told they might have cancer when they don’t. That means 99% of people testing positive for a cancer will be stressed and seek more care for no reason.
- If you are testing for the aforementioned 800 conditions/diseases and the test is 99% accurate for each of them (and assuming the average probability is that very same 1 in 10,000), the odds of at least one false positive are overwhelming. On average, you would likely have eight.
We do see some irony in Mito’s claim, in particular:
Raise your hand if you would feel better knowing you might have cancer, even though the odds are you might not…and there is nothing you can do about it now other than get a painful and possibly inconclusive biopsy (In all fairness to Mito, they have wisely dropped that claim from their actual website, though as you saw, it still shows up on a search,)
We could go into more depth on any of these points. As one example, a surprising number of cancers aren’t going to be your cause of death. Half of men over 50 have cancer cells in their prostates, and yet only a small percentage of men die of prostate cancer. Thyroids are the same, with 65% of adults having nodules.
The more cancers you look for, the more you find.
Nothing demonstrates that better than South Korea’s “natural experiment” in thyroid cancer screening. The government decided too many people were dying of it, so they decided to fund ultrasounds for early detection. Here is the predictable result: a massive increase in suspicious “inconclusive” results leading to a massive increase in the number of thyroids removed…and essentially no change in the death rate:
