The Food and Drug Administration said on Friday that it was moving to close what has widely been viewed as a loophole allowing certain lab tests — like those that determine the profile of a tumor or the genetic health of a fetus — to bypass review with virtually no tracking or oversight.
The agency proposed a rule that would bring the tests under its regulatory authority, requiring laboratories conducting them to provide data on test accuracy. Hundreds of tests on the market have very little oversight and may be misleading to the public and patients seeking to learn whether they have Lyme disease, Alzheimer’s or will develop cancer.
The proliferation of these tests “leaves Americans vulnerable to making important health care choices based on potentially faulty or inaccurate test results,” Dr. Robert Califf, the F.D.A. commissioner, said in a news briefing on Friday.
The tests, which included the first ones to detect Covid-19, have been subject to agency concern for 30 years and have been a perennial — yet essentially untouchable — target by lawmakers dating back to former Senators Edward Kennedy and Barack Obama and as recently as this year.
Academic medical centers that include labs operating the tests have opposed changes, citing the importance of being nimble in the face of a rapidly changing, pandemic-prone world.
Though renewed attention about the tests’ accuracy may be unsettling to patients, there have been few clues available to them — or even to their doctors — about whether the tests were vetted or received thorough F.D.A. oversight, according to Jeff Allen, president of the Friends of Cancer Research, a nonprofit partly funded by pharmaceutical companies.
“A rule like this is getting to it at the front end to be sure each test out there meets reliable accuracy standards — so those questions don’t need to be asked,” he said.
Mr. Allen said the pathology lab in a hospital may know the origins of a test, but that information is rarely passed on to doctors and patients. He said that his organization was concerned about the accuracy of tests administered to glean the genetic profile of a tumor that led to decisions on treatment.
An investigation by The New York Times found that prenatal genetic screening tests were frequently wrong, with many false-positive results.
Academic researchers, physicians and the F.D.A. have criticized other, similar tests, as well. Those include tests that are meant to calculate a person’s so-called genetic propensity for developing diabetes or becoming an elite athlete.
Doctors have also raised concerns about tests meant to predict the chances of developing Alzheimer’s disease. In 2015, the F.D.A. issued a report about 20 tests of concern, including one to detect ovarian cancer and another for Lyme disease. A longstanding concern about the tests is whether they have misled patients facing decisions about aborting a fetus with a possible genetic abnormality or getting a mastectomy or hysterectomy based on cancer screenings.
Opponents of additional F.D.A. oversight say the agency does not have the resources to review and oversee tests for emerging health concerns.
Susan Van Meter, president of the American Clinical Laboratory Association, which represents lab companies and test makers, said in a statement that billions of tests were run each year that influence a majority of the decisions made by health providers.
The association noted that the only test now available to detect fentanyl mixed with a dangerous animal tranquilizer, xylazine — a combination known as “tranq dope” — is one that would be subject to the new layer of oversight.
“F.D.A. seriously risks falling behind on its current public health priorities,” according to the association’s statement released on Friday. The association said it planned to ask the agency to withdraw the proposed rule and said it would continue to work with Congress on the matter.
An effort to update oversight of lab tests failed late last year in Congress after advocacy groups spent countless hours on a compromise. Called the Valid Act, the measure was expected to pass in an omnibus budget bill, but ultimately was not included. It was reintroduced earlier this year.
The regulatory paths for lab tests generally depend on who is analyzing the test. Tests manufactured by a company and performed by a consumer or health care provider tend to be regulated by the F.D.A., which requires the test maker to evaluate and report on its accuracy.
The less regulated tests, known as “lab-developed” tests, tend to be processed at a central location with results transmitted back to consumers or health care providers. Those tests may be overseen by lab experts for Medicare and may also be accredited by the College of American Pathologists.
The F.D.A. is not even sure how many lab-developed tests exist.
“No one truly knows how many of these tests are out there, or who makes which one, let alone which tests have a track record of inadequate results and problems and which don’t,” said Dr. Jeffrey Shuren, the head of the F.D.A.’s medical device and diagnostics division, during the briefing on Friday.
The proposed rule will be open for public comment and likely will be challenged in court, said Jeffrey Shapiro, a lawyer at King & Spalding who represents some labs that have developed tests.
He said the lab-developed tests are services or procedures that are already regulated by Medicare officials.
“This proposed rule is nothing new, it’s the same dispute that F.D.A. has been having with industry for 30 years,” Mr. Shapiro said. “Major economic questions like this one affecting the health of millions should be decided by Congress, not F.D.A.”
The agency also noted how long the debate over these unregulated tests has dragged on, with Dr. Califf acknowledging on Friday that the agency had to deal with how prolific the tests had become.
“Laboratory-developed tests play a central role in U.S. health care, and many are similar to other tests that come in to the F.D.A. for review,” Dr. Califf said. “This approach no longer makes sense and puts U.S. patients at risk.”