Some people see it as the holy grail in oncology — a simple blood test that can detect any kind of cancer at an early stage, when it is easiest to treat and possibly cure.
Illumina, the world's largest maker of DNA sequencing machines, said on Sunday that it was forming a company to attempt to develop such a test.
The company, called Grail, has raised over $100 million, mostly from Illumina and the venture capital firm Arch Venture Partners, but also from Microsoft's co-founder, Bill Gates, and Jeffrey P. Bezos, the founder and chief executive of Amazon. Grail, which is majority-owned by Illumina, has also assembled a prominent roster of advisers.
"If this pans out, this could be a real game changer," said Dr. José Baselga, the physician in chief at Memorial Sloan Kettering Cancer Center, who will head the company's science advisory board.
But some experts said that developing such a test would be a daunting task. Even Dr. Baselga seemed skeptical that a pan-cancer screening test could be ready by 2019, the goal of Illumina's chief executive, Jay T. Flatley. Screening for particular types of cancer may be easier, Dr. Baselga said.
The approach to be used takes advantage of the fact that DNA from cancerous cells can be found in the blood, albeit in minute amounts. The blood test, using intensive DNA sequencing, would look for patterns of telltale mutations.
Many companies are developing similar tests, known as liquid biopsies, that use a blood sample to replace or supplement a conventional biopsy, in which a sample of the tumor is extracted from the body by needle or surgery. In just the last week, one company, Guardant Health, said it had raised nearly $100 million in its latest funding round while another, Exosome Diagnostics, said it had raised $60 million.
But so far, liquid biopsies are mainly used for patients already known to have cancer. The tests help determine the particular mutations in the tumor to help select the best drugs to use. Or they are used to monitor whether treatment is effective or to check for a recurrence.
Detecting early-stage cancer, although an eventual goal of many liquid biopsy companies, is considered more difficult. Many cells, not just cancerous ones, shed DNA into the bloodstream, and many noncancerous cells have mutations that are also found in tumors.