Blood tests which can pick up early signs of cancer are growing in usage. Illumina Inc. recently disclosed that its Grail unit has  has sold 38K of its test (which costs $949) since it debuted in June of 2021. This comes despite the fact that most insurance companies don’t cover the cost so it is an out-of-pocket expense. Also known as liquid biopsies, they are designed to augment traditional screening tests. Analyst Puneet Souda at SVB Securities estimates they could eventually reach $50 billion in annual revenue, although he didn’t predict in which year this would occur.