A Look at the Status of Precision Diagnostic Techniques in Otolaryngology

by Jennifer Fink •

A clinician can use a blood test to obtain a baseline level of TTMV prior to treatment and then assess the impact of that treatment. “Once the treatment is completed, that TTMV level should go to being undetectable,” Dr. Chang said. Clinicians can then use the blood test to watch for a rise in levels that could signal a cancer recurrence.

“Studies so far show that tests detecting circulating DNA could be more sensitive early on than imaging,” said Tiffany Glazer, MD, assistant professor of otolaryngology–head and neck surgery at the University of Wisconsin–Madison, noting that tumors smaller than 2 millimeters can’t usually be detected by CT or PET scans.

It may be that instead of doing a CT of the head and neck every three to six months, it’s better to do a blood test, because the CT won’t catch a bone, liver, or lung metastasis that can happen with HPV-related cancers. —Steven Chang, MD

Imaging studies remain the current standard of care for head and neck cancer surveillance, however. One question that remains to be answered is whether blood tests can reliably substitute for some imaging scans.

“It may be that instead of doing a CT of the head and neck every three to six months, it’s better to do a blood test, because the CT won’t catch a bone, liver, or lung metastasis that can happen with HPV-related cancers,” Dr. Chang said. Some patients may also prefer a blood test to a scan, even if additional research shows that blood tests may not be as accurate as imaging in detecting recurrence.

It’s also not yet clear if physicians can (or should) use blood tests to direct treatment. “If you do surgery, and the patient’s level goes to zero, can we avoid chemo and radiation despite high-risk features such as a microscopically positive margin? Can we avoid just radiation despite intermediate risk features such as a close surgical margin? Those questions haven’t been answered,” Dr. Chang said.

Another question that has yet to be answered is the impact of liquid biopsies on clinical outcomes for people with head and neck cancer. “Does using this biomarker make a difference in terms of oncologic outcomes and survival for patients?” Dr. Zevallos said. “The only way to know is to do a prospective study.” (All studies to date have been retrospective.)

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