Progress on blood tests to detect cancer
A California company said its experimental blood test was able to detect many types of cancer at an early stage and gave very few false alarms in a study that included people with and without the disease.
Grail Inc. gave results in a news release in May and reported them at a recent American Society of Clinical Oncology meeting in Chicago. They have not yet been published in a journal or reviewed by other scientists.
Non-invasive diagnostic tools
Many companies are trying to develop early detection “liquid biopsy” tests that capture bits of DNA that cancer cells shed into blood.
Last month, Johns Hopkins University scientists launched a company called Thrive Earlier Detection Corp. to develop its CancerSEEK test, which yielded results similar to Grail’s more than a year ago.
Grail is closely watched because of the extraordinary investment it’s attracted — more than $1 billion from Jeff Bezos, Bill Gates and other celebrities.
The new results included 2,300 people, 60% with cancer and 40% not known to have it. The test detected 55% of known cancers and gave false alarms for 1%. Dr. Len Lichtenfeld, interim chief medical officer of the American Cancer Society, called the low rate of false alarms “remarkable.”
The detection rate was better — 76% — for a dozen cancers that collectively account for nearly two thirds of cancer deaths in the U.S., including lung, pancreatic, esophageal and ovarian.
The test found only about a third of cancers at the very earliest stage but as many as 84% that had started to spread but not widely.
It also suggested where the cancer may be in 94% of cases and was right about that 90% of the time.
That’s the most encouraging part because you don’t want to tell people they may have cancer and then need to do a lot of other tests to figure out where, said Dr. Richard Schilsky, chief medical officer of the oncology society.
“They still have a long way to go” to prove the test’s worth as a screening tool, but these results are encouraging, he said.
More studies underway
“I have little doubt that in the next several years we’re going to have what is probably a true early detection test,” Lichtenfeld said.
But the technology still needs to improve and to be tried in large groups of people without known cancers where the detection rate may not be as good, he added. Grail and Thrive already have larger studies underway.
Grail’s test has not been compared to mammography, colonoscopy or other screening tools, and is not intended to replace them, the company said.
On the other hand, many deadly cancers that the Grail test detected have no screening tests now, he noted.
The biggest question, Lichtenfeld said, is “will it make a difference in outcomes” such as helping people live longer — the ultimate measure of a screening test’s worth.