In honor of World Cancer Day on February 4, Hearing Health Foundation (HHF) wants to raise awareness of the connection between cancer and hearing loss. Every year, 8.2 million people worldwide die from cancer, a disease that is responsible for 13% of all deaths globally.
Depending on the type of cancer, patients that undergo chemotherapy are sometimes required to take certain drugs that could cause many side effects, including hearing loss. Cisplatin is a chemotherapy drug that is often used to treat testicular, bladder, ovarian and lung cancers. However, an excessive dose of cisplatin can be ototoxic (toxic to the ear), which could lead to temporary or permanent hearing loss.
One study suggested that cisplatin-induced hearing loss is generally bilateral (both ears) and irreversible. The study also found that cisplatin accumulates in cochlear tissue, preventing the cochlea from flushing out toxins. The same researchers found that patients receiving doses of cisplatin between 150-225 mg/m2 showed some degree of hearing loss. For testicular cancer patients, more than 50% of the patients that took cisplatin in doses greater than 400 mg/m2 had permanent hearing loss. Hearing loss may occur within hours or days after the treatment, or hearing may gradually decline after completion of therapy. After following up more than two years later, the study authors found that 44% of patients who took cisplatin had significant hearing loss.
In another recent study, researchers found that the WFS1 gene is associated with cisplatin-related ototoxicity; the heavier the dose, the more severe the hearing loss. Also, a mutation of the WFS1 gene results in Wolfram syndrome, a disorder with deafness as a major symptom.
As of now, there are no safe and protective agents against cisplatin, but scientists are hard at work to find a protective agent that would eliminate the negative side effects of cisplatin. Currently there’s a solution for children that are receiving cisplatin-based chemotherapy: The use of sodium thiosulfate may minimize or protect children and adolescents against cisplatin-induced hearing loss. HHF hopes more preventative therapies and cures for hearing loss can be discovered for all cisplatin-treated patients.