It has been known for a while now that certain medications are ototoxic, or damaging to the ears, particularly if taken long-term or in high doses. This list of ototoxic medications includes aspirin, anti-inflammatories such as ibuprofen, and Cisplatin, a common cancer-fighting chemotherapy drug. But because Cisplatin is so effective at targeting certain kinds of cancer, this drug–and other, similar platinum-based drugs–are still prescribed to an estimated 10 to 20 percent of cancer patients. Doctors and medical researchers can only warn patients of the risk of permanent hearing damage, and other symptoms such as dizziness, ear pain, and tinnitus (a phantom ringing in the ears).
Doctors, scientists and medical researchers are all anxious to find a way to reduce the ototoxicity of Cisplatin, and to see their patients have a better quality of life following cancer treatment. And a recent medical breakthrough that explains how Cisplatin damages the hearing may pave the way towards minimizing, or even eliminating, this life-altering side effect.
Cisplatin-induced hearing loss is permanent
The hearing loss that results from Cisplatin is usually bilateral, meaning it occurs in both ears. Research has also shown that it is irreversible. This is a serious health risk, especially for children who are more susceptible to Cisplatin’s ototoxic effects. Loss of hearing in childhood or infancy often interferes with the speech, and cognitive and social development of the child. This is another reason why doctors stress the imperative need for treatments that will lessen the ototoxicity of this drug.
Other than the fact that it affects infants and children more severely, the ototoxic effects of Cisplatin are variable, and hard to predict. The level of hearing loss that is sustained may be related to age, dosage, previous noise exposure, a depleted nutritional state and anemia.
Cisplatin and other platinum-based chemotherapy compounds are estimated to cause permanent hearing loss in 40 to 80 percent of adult patients, and at least half of children who are treated with the drug.
New findings illuminate how Cisplatin harms the ears
A recent study has helped to shed light on how exactly Cisplatin treatment leads to permanent hearing loss, and the findings have doctors and scientists thinking about new ways to reduce the harmful effects of this drug.
A team of researchers set out to uncover why Cisplatin is so toxic to the inner ear, and also why the hearing loss seems to get worse after each treatment, is more serious in children, and can occur long after treatment has stopped.
The study was supported by the National Institute on Deafness and Other Communication Disorders (NIDCD) and published in Nature Communications. It can be read in its entirety here.
The researchers used an extremely sensitive technique to locate cisplatin in mouse and human inner ear tissues, and found that Cisplatin actually builds up in the inner ear. While other organs and tissues locate and expel Cisplatin in matter of days or weeks, the inner ear was shown to retain this drug for months or even years. Cisplatin compounds also continue to build up with each successive treatment, as cells in the inner ear die from this prolonged exposure. In children, the inner ear Cisplatin build-up was found to be even higher than that of adults. The team also pinpointed a small region in the inner ear that could be targeted for efforts to prevent hearing loss from cisplatin.
James F. Battey, Jr., M.D., Ph.D, director of the NIDCD, said of the important study: “Hearing loss can have a major impact on a person’s life. Many adults with hearing loss struggle with social isolation and depression, among other conditions. Children who lose their hearing often have problems with social development and keeping up at school. Helping to preserve hearing in cancer patients who benefit from these drugs would be a major contribution to the quality of their lives.” Lisa L. Cunningham, Ph.D., chief of the NIDCD Section on Sensory Cell Biology, who led the research team, is optimistic that there is a way to reduce the ototoxicity of Cisplatin. “Our findings suggest that if we can prevent cisplatin from entering the stria vascularis in the inner ear during treatment, we may be able to protect cancer patients from developing cisplatin-induced hearing loss,” she said.
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