Sen. Edward J. Markey and other lawmakers are urging the Obama Administration to release draft recommendations that could spell out how a growing number of diagnostic tests for cancer and other medical conditions should eventually be regulated.

While many diagnostic tests on the market undergo U.S. Food and Drug Administration review, thousands of others do not. Many laboratories use an exemption in FDA regulations that allow them to offer tests without having proven they work, making it challenging for doctors and patients to differentiate good tests from bad.

The New England Center for Investigative Reporting recently reported on labs  using suspect Lyme tests that do not have FDA approval and the letter mentions those tests. But the lawmakers said other higher-risk, and more complex, tests are also coming on the market that need to be evaluated.

While the FDA has written draft language, called guidance, that often precedes regulation and sent them to the Office of Management and Budget for review, the proposal has languished there. The letter, which was also signed by Democratic senators Elizabeth Warren of Massachusetts, Richard Blumenthal of Connecticut, Sherrod Brown of Ohio and Dick Durbin of Illinois, was sent to the OMB.

“Laboratory diagnostic tests hold great promise in transforming our health care landscape, but the rules that could ensure their efficacy and safety have languished at OMB for years,” Markey said in a statement.  “We need this long-overdue guidance to be released to ensure the appropriate oversight of these tests can move forward in an open and transparent manner and these tests perform as advertised."

The FDA has tried for years to more stringently regulate the tests but has been opposed by the clinical lab industry. The American Clinical Laboratory Association, an industry group, filed a federal citizen petition last year challenging the FDA’s authority to regulate the tests. The tests, the group said, are already well regulated by other federal statutes and do not come under FDA’s jurisdiction because they are laboratory services, not products.

“FDA regulation of LDTs would be contrary to the public health, stifling innovation and negatively impacting patient access to this valuable category of diagnostic laboratory services, which includes many 'gold standard’ DNA sequencing assays, newborn screening tests, and tests for rare diseases,”  the petition reads.

The Office of Management and Budget did not immediately respond to a request for comment.

The lawmakers said in the letter that better regulation of tests, particularly high-risk ones, are needed.

"Incorrect results mean that patients either will not seek out the care and therapy that is needed, or will be subject to treatments that do not work or are harmful,'' the letter reads.