While platinum-based chemotherapy drugs have the power to save lives, they also pose a significant risk to survivors’ hearing and neurocognitive abilities. A recent study found that patients exposed to ototoxic cancer treatment drugs suffered mild to severe hearing impairment, putting them at increased risk for lasting neurocognitive deficits. With patient care at the apex, these findings highlight an opportunity for interventional audiology that could impact the quality of life, treatment adherence, and understanding of disease for patients and survivors. When caring for patients exposed to platinum-based chemotherapy, audiologists play a more critical role in the multidisciplinary care team than ever.
Though long-term survival from childhood cancer exceeds 85 percent in the United States, survivors remain at risk for chronic morbidities associated with treatment, including hearing impairment and neurocognitive deficits, a study recently published in JAMA Oncology found (JAMA Oncol. 2020;6:1363-1371). Treatment-induced hearing impairment was found to be associated with platinum-based chemotherapy such as cisplatin and carboplatin, or radiotherapy directed to the cochlea, and was typically bilateral, permanent, and progressive, according to the study.
“We stratified patients into treatment exposure groups, based on the treatment they received, including no toxic exposure, platinum-only exposure, and cochlear radiotherapy exposure with or without platinum-based chemotherapy,” said the corresponding study author Johnnie Bass, AuD, PhD. “We performed a variety of assessment measures, and study participants completed otoscopy, pure-tone audiometry, tympanometry, and speech audiometry.”
From those assessments, the study found that the frequency of mild hearing impairment among survivors was 7.3 percent for those in the no exposure group, 20.2 percent in the platinum-only exposure group, and 22.2 percent in the cochlear radiotherapy group. The risk for developing severe hearing impairment was also higher among survivors in the platinum-only and cochlear radiotherapy groups compared with those in the non-exposure group.
“Patients who receive platinum-based chemotherapy are at a much higher risk for ototoxicity than those who receive other cancer-treating drugs,” Amanda Edwards, AuD, said. “Cisplatin is known to have the most toxicity when it penetrates the end organ of the hearing cochlea, and from recent posthumous studies of those treated with the drug, we have found that it stays in the cochlea.” Despite its known toxicity, Edwards said it is vital to use platinum-based chemotherapy in some oncology cases, such as those where patients were resistant to other therapies. “Some teams find that the course of treatment of the primary disease—especially a life-threatening illness such as cancer—is first and foremost,” she explained.
INCREASED NEUROCOGNITIVE RISKS
That treatment—though life-saving—can cause lifelong hearing impairment-related neurocognitive defects, from difficulties with attention and emotional regulation to diminished intelligence and processing speed. Though study participants with even minor hearing impairment as a result of platinum-based chemotherapy showed an increased risk for neurocognitive deficits, those survivors who received cranial radiotherapy for central nervous system malignant neoplasms experienced the highest risk for neurocognitive dysfunction.
“Results of the assessment measures were categorized under six main domains: attention, memory, intelligence, executive function, academic function, and processing speed,” Bass said. “We found that survivors with severe hearing loss were at an increased risk of neurocognitive deficits, regardless of what treatment they received, but even those with mild hearing loss saw an association with neurocognitive function.” The study reported that those with severe hearing impairment were at higher risk for deficits on measures that were heavily language-dependent, such as verbal fluency, verbal reasoning skills, word reading skills, and mathematical computation skills.
Those with severe hearing impairment also showed deficits in less language-dependent measures such as attention, executive function, and processing speed; significantly slower visuomotor speed; and had a 55 percent higher risk for inadequate fine motor speed. Survivors with even mild forms of hearing loss showed a 110 percent to 247 percent increased risk for neurocognitive dysfunction in attention, executive function, processing speed, academic function, and intelligence.
In addition, child survivors of cancer treated with platinum-based chemotherapy who suffered parent-reported hearing impairment were twice as likely to have difficulties with attention, reading, and/or mathematics; required more special education services; and experienced worse quality of life than those with no hearing impairment. In adult survivors of non-central nervous system cancers, hearing impairment was associated with diminished memory, organization, emotional regulation, and diminished task efficiency, the study reported.
Edwards noted that patients with untreated hearing loss are also more likely to suffer poor physical health and effects related to quality of life. “Studies have shown an increased association with depression, social withdrawal, fatigue, stress, and impaired memory,” she said. “Studies have also found trends of higher health care costs, emergency department visits, inpatient stays, and greater risk of hospital readmission in 30 days in those with hearing loss compared to those in the general population.”
CONSIDERATIONS FOR AUDIOLOGISTS
As more information related to ototoxicity becomes available, Brittney Sprouse, AuD, stressed the crucial role audiologists play on the multidisciplinary team. “When joining the care team for a patient with cancer, the first and most crucial step is to communicate with the oncology team to determine their current practice for managing and referring patients to an audiologist,” she said. “Some members of the care team may not recognize how significantly hearing loss can impact a patient's everyday function. It is one of the biggest challenges to quality of life.”
To ensure that patients receive the best care, education is key. “Providing patients with training and awareness is critical to mitigating the challenges posed by hearing loss, but educating the staff by describing what audiology is and what services we provide is just as crucial,” she said. Sprouse noted that explaining an audiologist's role and the importance of hearing care to other members of the care team will allow for more referrals, better care coordination, and increased compliance from patients. “By communicating with the oncology care team, audiologists will be better able to share and explain testing and results, track patient progress, and make recommendations and treatment plans,” she said.
“Reaching out and offering educational services to different professionals about audiology services and what we can offer to better serve their patient population is key to developing a multidisciplinary team,” Edwards added. “It's important to be able to give patients the best care throughout the process. We're not telling oncologists to change their approach; we're talking about the best ways to help patients with hearing and communication so they can maintain access and communication effectively throughout their care.”
When working as part of the multidisciplinary cancer care team, audiologists can provide critical education on the specific risks of platinum-based chemotherapy that could impact treatment decisions. “It can be beneficial to encourage the team to explore all available therapies,” Edwards said. “In addition to looking at dosing and length of treatment, we have to consider other therapies, such as surgery to the head or neck,” she said. “If the oncologist uses platinum-based chemotherapy, it's important to always follow up with an early, engaging conversation with the patient about the lasting or late effects of going through the treatment. Doing so will put them in a better position throughout therapy and creates awareness during survivorship for possible side effects, such as hearing loss or tinnitus, that they could be managing for the rest of their life.”
Edwards noted that providing that needed interventional audiology is more crucial now than ever as COVID-19 measures such as how wearing face masks poses continuing challenges for those with hearing loss. “With the increased use of face masks, patients are unable to read lips and may need assistance. As hearing care professionals, we're equipped to be able to assess personal risks and start a conversation with patients early about communication and coping strategies,” she said. “We have the power to help patients minimize the negative effects of their treatment and maximize their hearing function.”
One way to do so is to work with patients who will be receiving platinum-based chemotherapy drugs as early as possible to establish a baseline, so any new or advancing hearing impairment can be monitored, Edwards said. “Setting up a hearing evaluation prior to the start of other therapies is important. We don't want to delay other services, but this is a step that could impact care in other areas,” she said. “If there is hearing loss, we would be able to move forward with an intervention such as amplification or cochlear implants early in the process, which could lead to better overall outcomes.”
Bass noted that a lack of baseline information—both for neurocognitive performance and for hearing ability—was one limitation of the study that will inspire future research. “We had no data for patients’ existing hearing loss, so we were unable to include worsening hearing impairment for analysis,” she said. “For those patients who reported existing use of a hearing aid, we did not have data on hearing aid variables, such as years of use or adherence, so we weren't able to compare neurocognitive deficits between patients who used hearing aids and those who did not,” she added. In future research, Bass said she would want to include a secondary analysis of patients’ track record of hearing loss and hearing aid use.
A study that did quantify hearing aid use among childhood cancer survivors for whom one was recommended found that use was surprisingly low, with only 23 percent reporting hearing aid or cochlear implant use, Bass said. To improve these statistics, she recommended working closely with the patient's parents. “Parents are your partners,” she said. “They're the main and key role in identifying and managing a child's hearing loss and related issues; they know their child best.” Bass added that educating them on the importance of audiology and providing guidance early in the cancer treatment journey can empower parents to identify the signs and symptoms of hearing impairment in their child. “Encouraging parents to report concerns, no matter how small, can lead to early detection of hearing loss,” she said. “I urge parents to be proactive and not reactive.”
Working with a patient's support system is critical when hearing impairment is present, since the patient may suffer neurocognitive deficits, such as a diminished ability to communicate or process information. “When you think of someone who is trying to manage a potentially life-threatening illness, is on medication, and may already have hearing loss or experience an advancement of that hearing loss, it's clear that their ability to engage in conversations with the medical team and understand advice, directives, and even what their disease is, could be hindered,” Edwards said. “They need to be able to communicate with their care team.”
Of course, a positive outcome is something each patient deserves—and one that can be achieved with proper hearing care. “I feel for patients and their families who have such a big battle ahead of them—cancer has multiple facets, and hearing loss is just one,” Bass said. “Patients may not think it's the biggest battle at the time, but once they beat cancer and become survivors, they find that hearing loss can have life-changing side effects and impact all areas of their life. If we can get audiology on the spectrum of oncology care—and make it one of the important appointments—we have a better opportunity at catching hearing loss and neurocognitive deficits early.”
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