Progressive Sensorineural Hearing Loss Following Cisplatin Chemotherapy: Mechanisms Underlying Cochlear Retention and Long-Term Ototoxicity

Cisplatin-induced ototoxicity is a permanent, bilateral sensorineural hearing loss occurring in up to 80% of treated patients. Its defining and clinically challenging feature is the progressive worsening of auditory function that continues well after chemotherapy has ended, a trajectory that cannot be explained by cumulative dose alone. This article is a comprehensive review of the present research studies on mechanisms that are responsible for this post-treatment progression. The cochlea, unlike other organs, appears to be unable to eliminate platinum (the active divalent metal ion released from cisplatin and responsible for its cytotoxic and ototoxic effects): traces of it can be found in human temporal bone tissue even more than 18 months after last infusion, and bone might serve as a long-term systemic reservoir. Within the inner ear, platinum accumulates preferentially in the stria vascularis, impairing endocochlear potential and outer hair cell function. Retained platinum sustains cascading effects including sustained NOX3-dependent oxidative stress, mitochondrial dysfunction, ongoing genotoxic injury to non-regenerative cells, and the early loss of ribbon synapses that precipitates delayed spiral ganglion neurodegeneration. Pharmacogenetic variability in platinum transport and antioxidant metabolism further modulates individual susceptibility. These findings support lifelong audiological surveillance and provide a basis for designing strategies that can protect hearing without compromising the essential anticancer efficacy of cisplatin therapy.