This has been pretty widely discussed in the financial press - investors think this will make a lot of money.
The test is a product of Grail, a 2015 startup in San Francisco. Illumina is trying to acquire Grail, but the regulators are not keen on the acquisition.
If you look at the way Grail is planning to do business - they are hoping to get approval from Medicare. Annual tests at $847 per enrollee.
This would be unaffordable, unless Medicare rates were raised by a whole bunch.
By the way - there are cancer cells present in almost everyone. It is only when the immune system can not overcome the cancer that the host (patient) is in trouble.