Ototoxicity Monitoring with Automated Audiometry: Clinical Workflows for Oncology, Cystic Fibrosis, and Beyond

The Scale of the Ototoxicity Problem

Hearing loss caused by medications and chemicals is one of the largest under-monitored health issues in clinical practice. Over 300 medications and substances are ototoxic — more than 200 prescription and over-the-counter medications, plus over 100 environmental substances ranging from everyday exposures (pesticides, organic solvents, tobacco smoke) to industrial agents (lead, mercury, benzene, toluene).

Four routes of exposure can each produce ototoxic damage: injection, ingestion, inhalation, and absorption. The two latter routes matter particularly for patients with industrial exposures, where solvents and metals can produce ototoxic effects through routes that are easier to overlook in conventional clinical history-taking.

The degree and type of ototoxicity depends on personal variables — genetic predisposition, other medical conditions, drug interactions, and noise exposure levels. Crucially, noise exposure and ototoxic agent exposure are synergistic: the combined hazard from both is greater than the sum of each alone.

Three Anatomical Systems Affected

Ototoxic agents can affect three distinct parts of the auditory and vestibular system:

• Cochlear toxicity. Damage to hair cells and membrane structures in the organ of Corti. Produces sensorineural hearing loss and/or tinnitus. Often, tinnitus appears in clinical history before measurable hearing loss on a conventional audiogram.
• Vestibular toxicity. Damage to cells in the vestibular organs. Produces balance and orientation symptoms.
• Damage to nerve fibers involved in hearing and balance signal transmission.

The Access Problem

The clinical reality: patients undergoing ototoxic treatments often don’t have practical access to audiology. Conventional monitoring requires a highly trained hearing healthcare professional, a double-walled sound booth, and full audiometric and audiological evaluation — all at frequency intervals compatible with treatment dosing schedules. The math doesn’t work for most patients in most settings.

This access gap is bidirectional. Oncologists, cystic fibrosis specialists, and other physicians administering ototoxic treatments often want to recommend hearing monitoring — but if they don’t have practical referral pathways to audiology, or if local audiology has waiting times that don’t accommodate dosing-aligned schedules, the recommendation doesn’t get acted on.

Intelligent Triage in Practice

Effective ototoxic monitoring uses automated audiometry as a triage layer, not a replacement for full audiology. The pattern that works in deployed clinical settings:

1. Automated air conduction screening at each monitoring point — reduced frequency set, patient-driven or assisted by trained non-audiologist staff, with continuous ambient noise monitoring.
2. Real-time review or change detection against an established baseline using change criteria (ASHA, CTCAE, Brock) or clinician inspection.
3. Escalation to full audiology evaluation (including bone conduction, masking, speech testing) when a significant change is detected.

This pattern lets the constrained resource (audiologist time, sound booth access) be deployed where it produces the most clinical value, rather than spread across every monitoring point regardless of whether a change has occurred.

The Cystic Fibrosis Story — Flores Study and Trikafta

Approximately 50% of adults with cystic fibrosis have drug-related hearing loss, primarily from furosemide and from aminoglycoside antibiotics administered during childhood and adolescence.
The Flores et al. study (Dr. Nan Shah’s team, UK) identified 126 CF patients and performed otoscopy and tympanic-membrane visualization (clinic staff), followed by self-assisted tablet audiometry from 1k to 12.5k Hz in air conduction. The study found hearing loss correlated with two factors: age and total intravenous antibiotic days over the past 10 years. The authors published a clinical protocol flowchart for non-audiology departments to implement systematic hearing monitoring.
The Trikafta development changes the long-term significance of this work. In the early 1990s, average CF life expectancy was about 30 years. With Trikafta — fast-tracked through FDA and Health Canada approval during the 2021 pandemic period — patients are now being told their life expectancy is many additional decades beyond ~50 years. The implication for audiology: a CF patient population that historically wasn’t prioritized for long-term hearing care now urgently is.

The Tuberculosis Story — Policy Change at the WHO

Tuberculosis is, outside of pandemic years, the world’s leading infectious-disease killer. Drug-resistant TB has historically been treated with kanamycin and amikacin — aminoglycoside antibiotics that are highly ototoxic.
Starting in 2015, SHOEBOX worked with the Union Against Tuberculosis and Lung Disease — the world’s leading NGO on TB research and treatment — on the STREAM clinical trial, deploying SHOEBOX tablet audiometers in 15+ countries, many of which had no resident audiologists. The trial tested air-conduction frequencies from 1k to 8k Hz, used the Brock change criteria to detect ototoxic shifts, and triggered consideration of a treatment switch to Bedaquiline (more expensive but less ototoxic) when significant change was detected.
The outcome was a policy change. The WHO World Report on Hearing now contains an official recommendation that aminoglycoside antibiotic injectables are no longer first-line treatment for drug-resistant tuberculosis, based directly on the demonstrated hearing impact in the trial work. Bedaquiline, despite higher cost, is now recommended worldwide for that indication. This is a rare case where audiometric data directly drove a global treatment-protocol change.

Oncology Monitoring — The Established Use Case

Oncology is the ototoxic case presentation most clinicians are familiar with. The platinum-based chemotherapy agents — particularly cisplatin and to a lesser extent carboplatin — are highly ototoxic. Cisplatin is used in testicular cancers, head and neck cancers, and other solid-tumor presentations where it is highly efficacious.

Ionizing radiation, often used early in cancer diagnosis with high-dose protocols, is the other major ototoxic exposure in oncology. The combined effect of cisplatin chemotherapy plus head-region radiation in patients with head and neck cancers means oncology audiometric monitoring should consider both agents in protocol design.

Newer Frontiers — Tepezza and FDA-Mandated Monitoring

The most recent development worth flagging is Tepezza — a drug used for thyroid eye disease (Graves’ ophthalmopathy) — which animal studies have shown to be ototoxic and for which the FDA has mandated regular audiometric monitoring. Infusion centers running Tepezza protocols are actively reaching out for audiometric monitoring partnerships, since most do not have in-house audiology.

This is a likely pattern for the future. As more therapies are fast-tracked through FDA approval with ototoxic findings either established or suspected, the FDA’s authority to mandate accompanying audiometric monitoring is increasingly being exercised.

Testing Requirements for an Effective Monitoring Program

For a tablet audiometer to be effectively deployed in oncology, cystic fibrosis, infusion-center, or infectious-disease settings, several technical and operational requirements apply:

1. Clinical validity that resists manipulation. Patients undergoing ototoxic treatment are sometimes very fatigued, sometimes unfamiliar with tablet interfaces, and sometimes anxious. The test must produce results that are reliable 100% of the time — meaning that when responses are inconsistent or implausible, the test does not produce results that could be interpreted as valid. SHOEBOX PureTest uses an award-winning, patented, modified Hughson-Westlake bracketing algorithm with catch tones to verify response consistency.
2. Frequency-by-frequency ambient noise monitoring. A free phone noise app that gives an overall dBA value is not useful for audiometric testing — what matters is whether the noise floor at each test frequency is below the relevant MPANL for that frequency. SHOEBOX PureTest performs frequency-by-frequency MPANL monitoring during every test using a calibrated Class 2 microphone.
3. Patient-driven test administration. A self-driven test reduces clinic staffing burden. Patients also typically complete the test about 30% faster on the second and subsequent administrations.
4. Assisted mode for patients who need it. For patients who are very fatigued, unfamiliar with iPad interfaces, or anxious about testing, an assisted mode lets a test administrator deliver the test using the same Hughson-Westlake bracketing algorithm while the patient simply gestures to indicate hearing.

Reporting and Remote Audiologist Review

Modern monitoring programs separate the testing activity (which can happen on any oncology ward or CF clinic with a trained champion) from the audiogram review activity (which can happen anywhere there’s an internet connection and a licensed reviewer).

The SHOEBOX web portal supports real-time audiogram upload, baseline tracking and superimposition, integrated change criteria (ASHA, CTCAE, Brock), remote audiologist review with notes captured in the portal, and multi-disciplinary access for oncologists, CF physicians, infectious-disease physicians, and audiologists. State licensing applies for the reviewing audiologist (must be licensed in the state where the test was performed), but the geographic constraint on test administration itself is removed.

The Call to Action

Three things together are reshaping the role of audiology in ototoxic monitoring: technology that supports valid testing outside the booth, regulatory pressure (FDA mandates for newer therapies), and survivability improvements that make long-term hearing care relevant for populations that previously had short post-diagnosis horizons.

For audiology clinicians, the practical question is no longer “should we get involved in ototoxic monitoring” but “how do we structure participation in a way that scales to the actual size of the need.” Remote audiogram review, infusion-center partnerships, CF clinic protocols, oncology consult relationships — all are opening as professionally relevant and clinically meaningful work.

“This webinar was presented by Renée Lefrançois during her tenure as Director of Audiology at SHOEBOX Ltd. All clinical references, drug names, regulatory citations, and pilot project outcomes reflect the information accurate at the time of the original presentation. Drug approvals, regulatory recommendations, and clinical practice guidance may have evolved since recording — readers should confirm current standards directly with the relevant regulatory bodies (FDA, WHO, ASHA), the published literature, and their SHOEBOX team for the most recent product details.”