By Laura Landro

Blood tests have long been an important tool for giving doctors a picture of a patient's health, from cholesterol levels to diabetes risk. Now new genetic science, AI analysis and other advances are providing even more sophisticated information from a simple vial of blood.

A wave of cutting-edge diagnostic tests can now identify diseases such as cancer and Alzheimer's at much earlier stages, sometimes long before symptoms appear, as well as manage chronic disease and tailor treatments to individual patients. And new data derived from blood can help tailor treatments to individual patients.

The new blood tests are backed by rigorous research, large clinical trials and collaborations with academic medical institutions -- a long way from the false promises of decade ago, when blood-testing startup Theranos made fraudulent claims of instant diagnostics.

A number of the most sophisticated tests have already received approval or clearance from the Food and Drug Administration or are seeking it. Some new tests have been developed by labs that are certified to meet federal quality standards, so they can market the tests without FDA authorization. The agency is currently reviewing its policies to ensure such tests meet higher regulatory standards for accuracy, reliability and safety before being widely used in healthcare, and researchers continue to explore the balance between risks, benefits and costs.

"This is a really exciting time as we develop blood tests that can be transformative for people in the early detection and more specific identification of disease," says Dr. William Morice, a physician who heads Mayo Clinic Laboratories in Rochester, Minn. While no test will ever be 100% accurate, he says, "it's important to work with your provider and make sure you are getting the tests which answer the questions you want to ask."

Here are some of the most important developments among the new tests.

Testing for cancer

A wave of blood-based cancer tests are helping doctors to detect, manage and monitor various cancers in a less-invasive way. These new liquid biopsies, as they are known, use artificial-intelligence tools to recognize complex patterns and molecular signals -- including tiny fragments of DNA shed by tumor cells and other cancer markers -- that would be difficult or impossible to find using traditional methods. The information can help doctors monitor patients' disease progression, detect recurrence and guide treatment decisions.

When it comes to screening patients for new cancers, the blood tests are used only in conjunction with traditional testing methods to confirm a diagnosis. For example, liquid biopsies are being used for early detection of colon cancer, but a colonoscopy is still required to make a definitive diagnosis and begin any treatment.

Last year, the FDA approved Guardant Health's Shield blood-based test for primary colorectal cancer screening in average-risk adults aged 45 and over, which costs $1,495. A study enrolling 20,000 average-risk adults found that the test detected 83% of colorectal cancers, as confirmed by a colonoscopy, with a 10% false-positive rate. The test's sensitivity for detecting precancerous lesions or polyps was only 13%, however.

In contrast, colonoscopies, which allow doctors to directly see and remove polyps, have nearly 95% sensitivity in detecting actual cancers. Some colon-cancer tests using stool samples have also demonstrated higher sensitivity than blood-based tests in detecting both colorectal cancer and advanced precancerous lesions.

Competition to develop advanced liquid biopsies for colon cancer is heating up, particularly for tests that are more accurate in detecting polyps, less costly or both. One 2023 study suggested they are currently not cost effective even for those who refuse other traditional screening methods, but other researchers have concluded they can still fill an important gap for people unwilling or unable to undergo existing screening options.

And with only about 60% of eligible adults now getting recommended colon cancer screenings, some doctors are excited about having a noninvasive screening option for patients who avoid colonoscopies or collecting their own stool sample.

Getting colon-cancer screening early is critical, but "you have to have a test that people actually take," says Guardant's chief medical officer, Dr. Craig Eagle.

Medicare began covering the Shield test for eligible beneficiaries last year, and the Department of Veterans Affairs began covering the test in March. Most private insurers haven't yet included Shield in their policies, and Guardant says it is working on getting it included in clinical guidelines from groups like the American Cancer Society and the U.S. Preventive Services Task Force, which often guides coverage decisions.

Finding more than a single cancer

A number of companies are marketing or developing blood tests that can detect multiple types of cancer, pick up small traces of disease after treatment, check for recurrence and tailor treatments.

As of now, there is not yet an FDA-approved multiple-cancer test. But these lab-developed tests, which are available for purchase with a doctor's prescription, are the focus of intense study to assess their effectiveness. Some researchers warn that the tests could identify cancers that wouldn't have caused symptoms or led to shorter lifespans, leading to unnecessary treatments and higher costs.

Grail's Galleri test, intended for annual use, can detect signals for up to 50 types of cancer, including a majority that lack routine or recommended screening methods. Two large trials, one in the U.S. and one in the U.K., are investigating how well the test performs in detecting cancer when used alongside existing screening methods. And the Dana-Farber Cancer Center in Boston is studying use of the tests for individuals with elevated cancer risk due to inherited genes or familial history, and for military veterans.

Galleri has a 76.3% sensitivity for 12 of the deadliest cancers that comprise two-thirds of all cancer deaths and a false-positive rate of about 0.5%. So, of every 1,000 people who don't have cancer, about five of them will have an incorrect positive result. Grail is pursuing FDA approval, which could broaden insurance coverage.

The lab-developed test has a list price of $949. Some employers cover Galleri, and the Tricare military health plan recently added it as a benefit. Medicare doesn't yet cover the test, but will cover the costs for a study of 50,000 participants aged 50 and older. The goal: to assess outcomes such as the improvement in diagnosing advanced cancers.

There are currently no guidelines for clinicians regarding the tests. A consensus statement published in April in the journal Cancer said that doctors shouldn't feel obligated to raise the issue of multicancer detection tests, but should be prepared to discuss what is known about the benefits, risks and uncertainties when patients ask about them.

St. Louis-based Mercy, a large health system, has adopted the test for its patients, with a focus on underserved communities. Mercy has completed 4,000 Galleri tests on patients, with 23 confirmed positive tests and only a handful of false positives. The health system offers free tests to some patients considered high-risk who are unable to pay. Dr. Jay Carlson, Mercy's medical director for oncology services, says the tests are critical for early detection of cancers "that would otherwise go undetected until it's too late."

Alzheimer's, autoimmune and more

Researchers continue to develop blood tests that can detect signs of Alzheimer's disease, provide earlier insights into autoimmune diseases, monitor the health of organ transplants and help diagnose respiratory diseases such as pneumonia.

Earlier this month, the FDA cleared Fujirebio Diagnostics' Lumipulse test to aid in diagnosing Alzheimer's disease for patients 55 and older who are exhibiting cognitive decline and other symptoms. While other tests for Alzheimer's have been on the market for several years, Lumipulse is the first to win full regulatory clearance, based on evidence that it can reliably measure blood biomarkers of the disease equivalent to more costly, risky and invasive procedures, according to the FDA.

Other companies, including C2N Diagnostics, Quest and Labcorp, market blood tests for Alzheimer's under the rules governing lab-developed tests. C2N launched the first commercial blood test for Alzheimer's in 2020 and issued an enhanced version, PrecivityAD2, in 2023. The company

says it expects to seek FDA approval in the near future.   A study published last year found the test was highly accurate in helping doctors identify Alzheimer's disease in patients with symptoms of cognitive decline. The test performed better than a standard clinical evaluation, such as memory assessments and physical exams, and its accuracy was found to be comparable to PET scans and spinal-fluid tests. 

Both the Lumipulse and Precivity tests measure key Alzheimer's biomarkers -- amyloid, a protein that clumps together and forms sticky plaques in the brain, and tau, a protein that forms into tangles in the brain. They differ in methodology and how results are reported; Lumipulse provides a negative, positive or indeterminate result indicating whether Alzheimer's changes are likely in the brain, and Precivity provides a numerical score estimating the likelihood a person has amyloid plaques and tau changes consistent with the disease.

FDA clearance can help pave the way for reimbursement for such tests. Fujirebio Diagnostics says the Lumipulse test should be available in the coming weeks, and pricing is still being established. PrecivityAD2 costs about $1,000 and is typically paid for out-of-pocket.

In approving the Lumipulse test, the FDA said it is not a stand-alone test, and other clinical evaluations or additional tests should be used for determining treatment options. But blood tests could slash long wait times to be assessed for Alzheimer's and allow a move to earlier, simpler and more accurate detection and diagnosis, according to Dr. Howard Fillit, a geriatrician who treats Alzheimer's patients and is chief science officer of the nonprofit Alzheimer's Drug Discovery Foundation.

Researchers are also working on more blood-based tests for other markers that could contribute to Alzheimer's, such as inflammation in the brain. "This is just the beginning of blood tests for cognitive impairment," says Fillit.

New blood tests are also being developed to help doctors be more proactive in the care of patients with autoimmune diseases, which are the third-most-common cause of chronic illness in the U.S. and are increasing in prevalence. Such diseases occur when the body's immune system becomes confused and starts to attack healthy cells and tissues. The autoimmune disease lupus, for example, can cause chronic inflammation throughout the body and is highly unpredictable, alternating between flare-up and remission. It carries the risk of long-term damage.

Mayo Clinic Laboratories collaborated with Progentec Diagnostics, a digital health and biomarker-technology company focused on autoimmune diseases, on its predictive blood tests for lupus. The tests use markers in blood to identify concentrations of 11 blood plasma proteins associated with immune-system activity in lupus. Powered by an AI-based algorithm to analyze possible warning signs in the patient's blood, the test can calculate the risk of a flare-up of the disease in the next 12 weeks.

Laura Landro is a former assistant managing editor of The Wall Street Journal and author of "Survivor: Taking Control of Your Fight Against Cancer." She can be reached at reports@wsj.com.

(END) Dow Jones Newswires

May 23, 2025 10:00 ET (14:00 GMT)

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