Many patients with advanced cancer are putting their hopes in a new experiment. In recent cases the experiment isn’t a new drug, but a new kind of test, called a liquid biopsy.
The test scans a person’s blood for small fragments of DNA released by tumors. The test manufactured by Guardant Health, a California startup heavily financed by venture captialists, looks for the DNA sequences of 68 well-known cancer genes and can reveal the mutations driving a person’s cancer.
Patients hope that these clues will lead doctors to be able to pick the right drugs in order to cure the disease.
At the moment laboratory diagnostics are very lightly regulated in the United States, these tests have gone to the market without consensus about their accuracy or data showing that they really help patients live longer.
According to an analyst at J.P. Morgan who track the industry, tests are coming to the market that are sometimes proven and other times unproven. Commercial activity is increasing very quickly. This analysis estimates $20 billion a year in tests globally by 2020, which is a significant increase from the $100 million today.
As of now, most insurers, including Medicare, don’t pay for these kinds of tests. They don’t think it is their role to underwrite what looks like a research experiments. One health insurer, Anthem, labels the tests “investigational and not medically necessary while another health insurer, Cigna, calls them “unproven.”
Eventually liquid biopsies should be able to catch signs of cancer early before symptoms arise, when a surgeon can cure it by cutting it out. This type of screening could profoundly reshape cancer medicine.
At the moment, liquid biopsies are being used as “theragnositcs,” also known as tests that guide decisions about treatment If doctors can spot a patient’s key mutation, they can pick one of about 50 drugs designed to work directly against these DNA defects. The number of targeted drugs has drastically increased from on about 15 in 2008.