A Look at the Status of Precision Diagnostic Techniques in Otolaryngology

Within a decade, otolaryngologists may use liquid biopsies to diagnose and guide the treatment of head and neck cancer, chronic rhinosinusitis, Ménière’s disease, sensorineural hearing loss, and other afflictions of the ear, nose, and throat. 

Already, scientists and clinicians are exploring the diagnostic possibilities contained within blood, saliva, perilymphatic fluid, and fluid from surgical drains. Blood tests that claim to offer early detection of up to 50 different kinds of cancer are already commercially available, as are blood tests that detect HPV-driven oropharyngeal cancer. Ongoing work to detect biomarkers in nasal mucus is occurring in parallel with the development of biologic agents and may eventually lead to endotypic diagnosis, rathethan phenotypic diagnosis, of sinus pathology. And a recently published “human atlas of the cochlea,” a molecular fingerprint of perilymphatic fluid of the inner ear, “could accelerate our way to a modern, molecular-based, and targeted approach for diagnosing and treating inner ear diseases,” according to the authors of the analysis (Front Cell Dev Biol. 2022;10:847157).

None of these diagnostic techniques are ready for widespread clinical use yet, however. “The use of these types of diagnostics is still not considered mainstream,” said Benjamin Bleier, MD, associate professor of otolaryngology–head and neck surgery at Harvard Medical School in Boston and the Claire and John Bertucci Chair in Otolaryngology–Head and Neck Surgery at Massachusetts Eye and Ear in Boston.

Yet work is progressing quickly. “The liquid biopsy landscape is changing every day,” said Jose Zevallos, MD, MPH, the Eugene N. Myers Professor and chair of the department of otolaryngology at the University of Pittsburgh and founder of Droplet Biosciences, a molecular diagnostics company based in Cambridge, Mass.

Here’s a look at the status of precision diagnostic techniques in various subspecialties within otolaryngology.

Head and Neck Cancer

Liquid biopsies are already being used to manage oropharyngeal cancer. NavDx is a commercially available blood test that can detect fragments of tumor tissue-modified human papilloma virus (TTMV) DNA and therefore aid in the detection of HPV-16–positive oropharynx cancer. According to Naveris, the Waltham, Mass.-based company that developed NavDx, the test can be used to “optimize clinical management across the care continuum,” and physicians in some places are currently using it (and similar blood tests developed by others) to assess response to treatment, identify molecular residual disease post-treatment, and aid cancer surveillance after treatment.

“There’s a lot of discussion about how to incorporate the test into the standard of care,” said Steven Chang, MD, vicechair of the department of otolaryngology–head and neck surgery at Henry Ford Health in Detroit. “What most institutions are doing right now is primarily using the tests for surveillance purposes, but each with slightly differing protocols.”

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.)

Researchers and clinicians also wonder if blood tests for oropharyngeal cancer are, or will soon be, accurate and reliable enough to definitively diagnose head and neck cancer. “The question is, can it be good enough to diagnose a cancer without having to take a biopsy in clinic or go to the operating room?” Dr. Glazer said. That could be a huge advantage, given the fact that “a lot of head and neck cancer patients aren’t the healthiest, and tumors could involve risky areas within the airway, so taking a biopsy isn’t always the safest procedure to do,” Dr. Glazer said. “Drawing a blood sample may be a cheaper, quicker, safer way to make a diagnosis.”

According to a recently published study in the International Journal of Cancer, circulating tumor HPV DNA may be detectable in the blood years before HPV-positive head and neck squamous cell carcinoma (HNSCC) is usually diagnosed. The study examined prediagnostic plasma samples of 12 HNSCC patients; the samples were collected 19, 34, and 43 months before cancer diagnosis. Circulating tumor HPV-16 CAN was detected in three of the 10 patients (30%) who were eventually diagnosed with HPV-16–positive tumors, including three of seven patients (43%) with HPV-16–positive oropharynx cancer (Int J Cancer. 2022;151:1081–1085). Additional clinical trials are currently underway.

The utility of early diagnosis is also a subject of speculation. “We can hypothesize that finding cancer earlier may make a difference, but that certainly hasn’t been proven yet,” Dr. Zevallos said. “Does detection of a cancer signal seven months earlier have any meaningful impact on survival? Is there a downside for the patient in knowing that a cancer is going to manifest, but you can’t do anything about it?”

Even as researchers work to answer these questions, other researchers are exploring additional diagnostic avenues. Both Summit Biolabs in Aurora, Col., and Naveris have developed saliva tests to detect head and neck cancer, and clinical trials to date have found that the tests can detect HPV-associated cancers with high accuracy (Onco’Zine. News Release. June 6, 2021). Dr. Zevallos and his team are also investigating liquid biopsies of surgical drain fluids.

Within the field, we now have proof of concept that if you can determine a patient’s inflammation category and then block that pathway with a very highly specific antibody, you can actually modify the disease. —Benjamin Bleier, MD

“The idea of using the surgical drain as a window into the body has never really been tapped; drain fluid is typically treated as a biowaste,” Dr. Zevallos said. “We’ve measured the amount of tumor DNA in a drain immediately after surgery all the way through 48 hours after surgery, and what we’ve found is that, in the majority of cases, patients will clear the tumor DNA. The ones who don’t clear it are of interest to us.” Continued detection of exosomes in the surgical drain fluid may suggest remaining cancer.

“It’s early, but the data are very promising so far in head and neck cancer,” Dr. Zevallos said.

Rhinology

Precision diagnostic techniques aren’t yet ready for prime time in rhinology. “Within the field, we now have proof of concept that if you can determine a patient’s inflammation category and then block that pathway with a very highly specific antibody, you can actually modify the disease,” Dr. Bleier said. But while there are some companies that will run a microbiome analysis or microtyping on nasal mucous samples, “it hasn’t gotten to the point where you can do this for an array of cytokines or other inflammatory biomarker,” he added.

Researchers are still working to identify clinically useful and meaningful biomarkers, with that work often paralleling the development of different therapeutic modalities, particularly biologic agents. Ultimately, Dr. Bleier believes that “the presence and elaboration of therapeutic options will drive the elaboration of more precise biomarker analysis and testing.” At present, with a limited number of FDA-approved biologic agents to treat chronic rhinosinusitis, it’s simply easier to prescribe the biologic that’s most likely to work given a particular clinical context and switch if needed, rather than trying to use precision diagnostics to direct treatment.

Ongoing research will likely shift rhinologic diagnosis from phenotypic diagnoses to endotypic diagnoses, and it’s likely that analysis of nasal mucus will play a key role. “Multiple studies have come out that have looked at cytokine levels in mucus alone and been able to differentiate patients into various groups,” Dr. Bleier said. One study that measured 17 mucus cytokines and inflammatory mediators in 147 patients with chronic rhinosinusitis, for instance, found that patients 60 years and older had elevated mucus levels of IL-1β, IL-6, IL-8, and TNF-α when compared to their younger counterparts (J Allergy Clin Immunol. 2019;143:990–1002.e6).

Otology

“The inner ear remains the last organ system you can’t biopsy,” said Hinrich Staecker, MD, PhD, the David and Mary Zamierowsky Endowed Professor in the department of otolaryngology at the University of Kansas School of Medicine in Kansas City. Liquid biopsy presents a unique opportunity to better understand the pathophysiology of the inner ear.

Dr. Staecker and others have invested significant efforts in elucidating the composition of perilymph fluid, utilizing samples obtained during cochlear implantation and surgeries to treat vestibular schwannoma. One study that utilized mass spectrometry to analyze the proteome of human perilymph in 36 patients with sensorineural hearing loss undergoing cochlear implantation found the proteins short-chain dehydrogenase/ reductase family 9C member 7 and esterase D in nearly all samples from patients with Ménière’s disease but none of the samples from patients with enlarged vestibular aqueduct or otosclerosis (ACS Omega. 2021;6:21241–21254). The potential of these two proteins to serve as a biomarker for Ménière’s or other inner ear diseases is an active area of research.

In April 2022, researchers (including Dr. Staecker) proposed a human atlas of the cochlea, based on bioinformatic analysis of the perilymph proteome. The team identified 878 proteins in perilymph samples, including 203 perilymph- specific proteins; one-third of the tissue-specific proteins had not been previously reported to be associated with the inner ear in either animal studies or in vitro experiments (Front Cell Dev Biol. 2022;10:847157). The group also identified druggable targets within the perilymph proteome.

Because perilymph fluid is difficult to obtain, researchers are now working to determine if it’s possible to identify potential biomarkers of inner ear pathology accurately and reliably in saliva or serum samples. “I think we’re getting close,” Dr. Staecker said. “We have a large Ménière’s study going on now where we’re looking at about 100 serum samples.”

As in rhinology, the search for effective otologic treatments is unfolding alongside the hunt for meaningful biomarkers. “There are a lot of companies testing out different medications for sensorineural hearing loss, but one of the big problems we have is that we’re missing solid biomarkers,” Dr. Staecker said. “So, it becomes a chicken-or-egg problem. We need the biomarkers to run a clinical trial at peak efficiency, and a lot of clinical trials that have failed may have done so because very similar-looking inner ear disorders are probably distinct from a molecular cellular standpoint.”

At present, analysis based on tissue biopsy or cytology samples is still the gold standard in the diagnosis of head and neck cancer (Cancers (Basel). 2021;13:1874). Chronic rhinosinusitis, Ménière’s disease, and other conditions of the nasal cavity, sinuses, and inner ear remain clinical diagnoses. Yet ongoing research will likely lead to innovative precision diagnostic techniques that will ultimately allow otolaryngologists to detect pathology through minimally or noninvasive measures and precisely treat disease.

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Jennifer Fink is a freelance medical writer based in Wisconsin.