Detecting Cancer From Blood Test

Every year, thousands of Americans undergo routine screening to catch cancer in its early stages, while it’s still treatable. But these routine tests can be painful and invasive, and doctors only regularly screen for five of some of the most common types of cancer.

So for decades, scientists have been working on ways to screen for cancers using a simple blood draw rather than a painful biopsy or invasive test. These so-called "blood biopsy" tests are closer than ever to dramatically improving the way doctors screen for cancer.

Galleri, a new blood test by health care company GRAIL, is one of the most advanced blood biopsy tests. It works by looking for fragments of DNA in a person’s blood that indicate the presence of more than 50 types of cancer.

Less than two thirds of Americans get screened for colon cancer, which often involves an invasive procedure called a colonoscopy. A simple blood biopsy such as Galleri may improve current cancer screening due to ease of use. But despite the recent advancements, many doctors say there’s a long way to go -- and some say there are reasons to wait for more research to be done.

The Galleri test, though promising, is not yet FDA approved. It still needs to undergo more testing to show it can produce reliable results every time. A common refrain in cancer treatment is "earlier is better": that the earlier a cancer can be found, the treatment is often more successful. However, sometimes it can be difficult to tell the difference between an early cancer and a non-cancerous growth.

A final diagnosis often involves an invasive procedure, such as a needle biopsy or surgery in order to remove tissue. These procedures are not without risk, and any screening tool, such as the Galleri test, should reduce the number of unnecessary procedures by not flagging non-cancers as cancers.

That’s why some in the medical community have hesitation about the utility of a blood biopsy capable of detecting only a few cancer cells, as it may accidentally detect a non-cancer as a cancer.

But at the very least, Galleri could provide an early warning system, so doctors could monitor patients and treat them if it becomes necessary. Although Galleri is still not FDA approved, the test can be prescribed by any physician in the United States. Because it’s not covered by insurance, it costs $949 out of pocket.