Radiation Therapy

Thresholds for Hearing Loss:

• A study found that the probability of SNHL increases sharply when the cochlea receives doses above 48 Gy, with a steeper dose-response curve for older patients or those with pre-existing hearing issues[3].

• For nasopharyngeal cancer patients treated with doses between 63–70 Gy, significant hearing loss was observed within

Combining radiation therapy with platinum-based chemotherapy drugs like cisplatin significantly increases the risk of hearing loss. Cisplatin is highly ototoxic and exacerbates cochlear damage caused by radiation

In summary, the likelihood and severity of hearing loss increase significantly with higher radiation doses, particularly when exceeding 50 Gy to auditory structures. Regular audiometric monitoring during and after treatment is essential for early detection and management.

Radiation therapy for head and neck cancers often damages the cochlea or acoustic nerve, leading to sensorineural hearing loss (SNHL). SNHL is dose-dependent, progressive, and typically permanent.

Otitis Media with Effusion (OME):

• Radiation can damage the mucosa and alter ciliary function in the middle ear epithelium, leading to fluid buildup (serous otitis media). This is one of the most common causes of conductive hearing loss following radiation therapy, particularly in patients treated for nasopharyngeal cancer[1][6].

• Fibrosis and

Radiation therapy for nasopharyngeal cancer frequently causes OME, which can lead to conductive hearing loss. Rates of OME range from 29% to 53% with intensity-modulated radiation therapy (IMRT)

Radiation therapy can lead to hearing loss in certain cases, especially when treating diseases in or near the head, ear, or brain.

Moderate to High-Dose Radiation:

• Sensorineural hearing loss (SNHL) becomes more prevalent with higher doses. Doses exceeding 50 Gy to the cochlea are strongly associated with significant SNHL, often characterized by a ≥15 dB threshold shift across multiple frequencies[3].

• High doses (>60 Gy) can cause permanent damage to the sensory hair cells,

Proton Radiation Therapy (PRT)

1. Precision and Cochlear Sparing: Proton therapy delivers radiation with high precision and has a finite beam length, which minimizes radiation exposure to surrounding healthy tissues, including the cochlea. This characteristic makes PRT advantageous for hearing preservation in some cases[1][4].

1. Risk of Hearing Loss: