Washington (WOWO) — Federal health advisers have backed a blood test designed to detect signals associated with more than 50 types of cancer, but experts cautioned Wednesday that major questions remain about how effectively the technology can identify cancer and whether using it will ultimately save lives.

The Food and Drug Administration’s advisory panel voted 7-2, with one abstention, that Grail Inc.’s Galleri test offers more potential benefits than risks. The vote could help clear a path toward FDA approval and broader use of the test, although the FDA is not required to follow the panel’s recommendation.

A final FDA decision is expected in the coming months.

Galleri is not a diagnostic test. Instead, it uses a single blood sample to look for DNA-based signals that could indicate the presence of cancer somewhere in the body.

A positive result does not mean a person definitely has cancer. Additional testing is required to determine whether cancer is actually present and, if so, where it originated.

The advisory panel’s support came despite extensive discussion about the test’s limitations, including the possibility of both false-positive and false-negative results.

The experts previously voted that the test appears safe and effective for use in people age 50 and older. However, they stopped short of endorsing the phrase “early detection” for the test, citing concerns about its performance in identifying cancers at their earliest stages.

That distinction is important because existing cancer-screening tests, including mammograms and colonoscopies, are specifically designed to identify certain cancers before they become advanced, when treatment can be more effective.

The Galleri test is different because it is intended to look for signals from many different cancers at once.

Grail has argued that the technology could provide an option for detecting cancers for which there currently are no recommended screening tests, including liver and ovarian cancers.

“Patients want opportunity, they want options,” said Dr. Mylynda Massart of the University of Pittsburgh, who presented on behalf of Grail. “They want the chance to fight their disease while the chance to survive is possible.”

But FDA reviewers emphasized that the test also can miss cancers.

Grail’s main study involved about 140,000 older adults. Researchers found that the test detected roughly one-third of cancers diagnosed during the following year.

Among people who received a result indicating a “cancer signal detected,” about two-thirds were subsequently confirmed to have cancer.

FDA reviewers focused on the other side of those numbers, noting that the test missed approximately two-thirds of cancers that were diagnosed during the subsequent year.

That creates the possibility of false reassurance, particularly if someone interprets a negative result as evidence that cancer is not present.

The advisory panel therefore recommended that patients be clearly informed that a negative Galleri result does not guarantee they are cancer-free.

Experts also stressed that the blood test should be used alongside existing recommended cancer screenings rather than as a replacement for them.

Those screenings include established tests such as mammograms for breast cancer and colonoscopies for colorectal cancer.

Another unresolved question is whether using Galleri actually reduces cancer deaths.

Grail has not provided data demonstrating that screening people with the test leads to fewer cancer deaths. Establishing that benefit would require following large numbers of people for years.

Dr. Victor van Berkel of UofL Physicians in Louisville, Kentucky, acknowledged the uncertainty surrounding the technology while supporting the panel’s recommendation.

“Perhaps my yes is a hopeful rather than an accurate one,” van Berkel said. “If we can find more early-stage cancers in the population that we can’t screen for currently, that will end up having benefit.”

Consumer advocates raised concerns about how patients might respond to a negative result.

Diana Zuckerman of the nonprofit National Center for Health Research warned during public comments that people who receive an all-clear result could delay seeking medical attention if they later develop symptoms.

“When they start having symptoms there will be tendency to delay going to the doctor — just a little bit — and that could be deadly,” Zuckerman said. “They will be told to continue other screening, but will they?”

The Galleri test is already available in the United States, although people generally must pay out of pocket, with the test typically costing $700 or more.

FDA approval could potentially expand access and increase the possibility of coverage by Medicare and private insurers.

The FDA’s advisory panel vote also represents a significant development for a broader field of so-called multi-cancer detection tests. Several companies are developing blood tests intended to identify signs of multiple cancers from a single sample.

Supporters see the technology as a possible way to find cancers that currently lack routine screening options.

Critics and regulators, however, have emphasized that finding a signal is not the same as proving that a screening test improves outcomes.

The central question now is whether identifying more cancers through blood testing will ultimately translate into earlier treatment and fewer cancer deaths.

For now, experts say people who undergo the Galleri test should continue following established cancer-screening recommendations, regardless of whether their blood test produces a positive or negative result.

The FDA will make the final regulatory decision after considering the advisory panel’s recommendations and the available evidence.