Chemotherapy-Induced Hearing Loss and Health Inequality

This project will inform and guide future care for cancer patients by investigating how cancer patients are affected by chemotherapy-induced hearing loss. Platinum-based chemotherapy drugs are known to cause damage to the ear. One of the most toxic chemotherapy drugs is cisplatin, which is used to treat testicular, ovarian, lung, bladder, head & neck, oesophageal, cervical, and stomach cancers. Platinum-based chemotherapy agents cause oxidative stress and cell death in cochlear cells in the ear, which leads to permanent damage to the hearing system.

This damage presents as hearing loss, and hearing loss is not routinely screened for or detected in cancer patients. Furthermore, individuals from more deprived backgrounds (based on Indices of Multiple Deprivation (IMD) quintiles, which represent levels of socioeconomic deprivation across the UK) are more likely to experience hearing loss due to multiple factors related to health inequity. These include barriers to accessing health services and education; lifestyle factors, such as working in manual jobs where noise exposure is high; and experiencing poor cardiovascular health. Individuals with lower socioeconomic status are also likely to recover less well from the acute effects of chemotherapy due to reduced overall health and physiological resilience. Therefore, cancer patients living in Quintile 1 (Q1; the most socioeconomically deprived 20% of areas in the UK according to the IMD) may be particularly vulnerable to experiencing chemotherapy-induced hearing loss and therefore a reduced quality of life, after receiving platinum-based chemotherapy. No research has explored whether cancer patients from more deprived quintiles may be disproportionately affected by chemotherapy-induced hearing loss. Furthering understanding of the association between hearing health and socioeconomic deprivation will help to guide future hearing screening and intervention following platinum-based chemotherapy.

Individuals with hearing loss may be at greater risk of experiencing cognitive decline and dementia. Previous research indicates that long-term hearing loss is associated with structural changes in auditory brain areas, including brain atrophy. Such changes may reduce the quality of neural input to other regions involved in auditory processing and language comprehension, such as the temporal lobe. Consequently, individuals with hearing loss may not only struggle to perceive sounds clearly but may also experience difficulties understanding speech and engaging in social situations.

Additionally, individuals with hearing loss may rely more on cognitive resources to understand speech in noisy environments. If capacity-limited cognitive resources are redirected to support listening, there may be reduced cognitive resources available for other daily tasks. This is important in the context of cancer, as chemotherapy is already known to cause cognitive dysfunction, so-called 'chemo brain', which is also a risk factor for cognitive decline. This means that cancer patients receiving platinum-based chemotherapy drugs relative to non-platinum chemotherapy drugs have a potentially greater risk of cognitive decline: 1) from the risk of neural dysfunction associated with chemo brain, and 2) from the risk of ototoxicity associated with hearing loss. Further, hearing loss is associated with social withdrawal due to difficulties listening in noisy environments, which has been linked with increased feelings of loneliness and reduced mental well-being.

This research is particularly relevant to the North West of England, where approximately 32% of the population lives in the most deprived areas in England. This is reflected in cancer diagnosis rates, with the North West population being 25% more likely to be diagnosed with cancer than those in the rest of England. Health inequalities in this region may also contribute to a higher prevalence of hearing loss compared to those from the South of England. Among 61-70-year-olds, 21.8% in the North West experience hearing loss, compared to 14.6% in the South East. For those aged 71-80, the prevalence is even greater, with 43% in the North West affected compared to 35.7% in the South East. Furthermore, the proportion of deaths due to dementia and Alzheimer's disease in the North West was 12.6% in 2019 (n = 9060), which was the fourth highest in England and Wales.