What fire fighters should know about multi-cancer detection tests

Fire fighters face an increased risk of cancer. Companies developing and selling new cancer detection tools know that, too. Some are marketing multi-cancer detection (MCD) screening tests directly to fire fighters, even before the tests have received regulatory approval or demonstrated that they improve health outcomes. Fire fighters are exposed to toxic smoke, chemicals, and carcinogens, increasing their risk of cancer. Catching cancer earlier through proven screening methods, like colonoscopies and annual physicals by primary care physicians, may increase the odds of survival. However, a little over half of all cancer deaths are caused by cancers that have no approved screening method. That has generated interest in tests claiming to detect multiple types of cancer before symptoms appear.

An MCD test uses blood, urine, or other bodily fluids to look for signals from cancer cells. Computer algorithms then interpret the data and produce a positive or negative result. The signals may include patterns of DNA methylation, levels of protein biomarkers, and changes in DNA or RNA sequences.

Unlike traditional cancer screenings, an MCD test may indicate that cancer could be present without identifying it conclusively. A positive result requires follow-up testing by a healthcare professional.

No MCD test has been approved yet by the U.S. Food and Drug Administration or authorized by Health Canada to detect cancer. Some are nevertheless available in the United States as laboratory-developed tests, or LDT, performed by laboratories certified under the Clinical Laboratory Improvement Amendments, or CLIA.

A CLIA LDT has not conclusively shown that it can detect cancer, is not subject to reporting of adverse events (e.g., someone gets a positive result despite not having cancer and has to go through unnecessary tests and procedures), and is not subject to review and approval of the accuracy of labeling and marketing claims. CLIA certification only means that the clinical laboratory that designs, manufactures, and uses the LDT meets standards for accurate, reliable, and timely testing of the markers the test specifically measures, not that the markers are valid for cancer detection. Research into the effectiveness of MCD tests is ongoing. Presently, no MCD tests are recommended or endorsed by the IAFF, nor are any screening methods outside of those listed in the National Fire Protection Association (NFPA) 1580 Standard on Emergency Responder Occupational Health and Wellness or as recommended by the U.S. Preventive Services Task Force (USPSTF). Put simply, none of these MCD tests should be relied upon by IAFF members at present.

When evaluating an MCD test, there are three important concepts to understand. The first two are sensitivity and specificity.

Sensitivity measures how often a test correctly produces a positive result in someone who has cancer. If an MCD test reports 95% sensitivity, it means that in 100 patients with cancer, the test will correctly identify cancer in 95 of those people. This means that five people with cancer will falsely be told they don’t have cancer. This can delay necessary care and lead people not to go to a doctor when symptoms appear.

Specificity measures how often a test correctly produces a negative result in someone who does not have cancer. If a test has 95% specificity, it will correctly identify 95 out of 100 people as cancer-free. This also means it will tell those remaining five people that they have cancer when they do not. This can lead to expensive and invasive testing that the person doesn’t need, as well as anxiety.

The success and failure rates will vary across tests and may even differ for different cancers within the same test. If you are choosing an MCD test, look for one with high specificity and sensitivity.

It’s important to note that a positive MCD result is not a cancer diagnosis. Further tests from healthcare professionals, such as imaging or a tissue biopsy, would be required to diagnose you with cancer. A negative result also does not guarantee that a person is cancer-free.

The third concept to understand is whose data was used to develop and evaluate these tests. For example, one test was developed using East Asian patient blood samples, and another was developed using patient blood samples from patients with an average age of 62 years. The algorithms that they developed using these patients may not be relevant to you if you are younger or not East Asian. The reported specificity and sensitivity should also be studied in a group similar to yours. If a test has reported high specificity in a group with an average age of 75 years old, it might not be accurate for a 25-year-old.

It is important to understand that none of these tests are approved to detect cancer, and they do not replace traditional screening methods, such as colonoscopies, mammograms, or recommended lung cancer screening. MCD tests should not be used in place of an NFPA 1580 annual medical exam, but may be considered as a supplemental test if recommended by your physician.

If you are interested in an MCD test, talk to your doctor first.

“The IAFF’s Science and Research Division works daily to be the source of reliable information for our members,” General President Edward Kelly said. “And, of course, we aggressively pursue the goal of bringing about the day when an MCD successfully passes scientific scrutiny to the extent that our members can rely upon.

“That day is not yet here,” he added, “but the IAFF will continue to be front and center on both the research and the education needed to protect our members.”