The test, introduced in June, has raised hopes among women and their doctors because it promises to detect ovarian cancer at an early stage, when it is still treatable.
But some outside experts, including the Society of Gynecologic Oncologists, have said the test had not been proved accurate and might cause women to have unnecessary surgeries to remove their ovaries. The F.D.A. itself, in a previous letter to LabCorp, said the test “may harm the public health.”
In its new letter, which was sent Sept. 29, the F.D.A. said the test, called OvaSure, required agency approval before it could be marketed.
Typically, the agency has not regulated tests that are developed and performed by a single laboratory, as opposed to test kits that are sold to hospitals, laboratories and doctors. But the F.D.A. said that OvaSure did not qualify for this exemption because the test was developed at Yale University, not at LabCorp, and the materials for the test were not manufactured by LabCorp.