Hearing Loss in Patients Who Received Cranial Radiation Therapy for Childhood Cancer

Abstract

Purpose: Patients treated with cranial radiation therapy (RT) are at risk for sensorineural hearing loss (SNHL). Although SNHL is often characterized as a delayed consequence of anticancer therapy, longitudinal reports of SNHL in childhood cancer survivors treated with contemporary RT are limited. We report the incidence, onset, severity, and long-term trajectory of SNHL among children receiving RT. Potential risk factors for SNHL were also identified.

Patients and methods: Serial audiologic testing was conducted on 235 pediatric patients who were treated with conformal or intensity-modulated RT as part of an institutional phase II trial for localized primary brain tumors, including craniopharyngioma, ependymoma, and juvenile pilocytic astrocytoma. All but one patient had measurable cochlear radiation dose (CRD) greater than 0 Gy. The median follow-up from RT initiation to latest audiogram was 9 years with a median of 11 post-RT audiograms per patient. Audiograms were classified by the Chang Ototoxicity Grading Scale. Progression was defined by an increase in Chang grade from SNHL onset to the most recent evaluation.

Results: At last evaluation, SNHL was prevalent in 14% of patients: 2.1% had mild and 11.9% had significant SNHL requiring hearing aids. Median time from RT to SNHL onset was 3.6 years (range, 0.4 to 13.2 years). Among 29 patients with follow-up evaluations after SNHL onset, 65.5% experienced continued decline in hearing sensitivity in either ear and 34.5% had no change. Younger age at RT initiation (hazard ratio [HR], 2.32; 95% CI, 1.21 to 4.46), higher CRD (HR, 1.07; 95% CI, 1.03 to 1.11), and cerebrospinal fluid shunting (HR, 2.02; 95% CI, 1.07 to 3.78) were associated with SNHL.

Conclusion: SNHL is a late effect of RT that likely worsens over time. Long-term audiologic follow-up for a minimum of 10 years post-RT is recommended.

Fig 1.

(A) Number of patients with SNHL (Chang grade > 0) or normal hearing grouped by age at initiation of RT (years) (N = 235). (B) Number of patients with SNHL (Chang grade > 0) or normal hearing grouped by cochlear radiation dose (Gy), which refers to the higher cochlear dose that a patient received between the left and right ears (N = 235). RT, radiation therapy; SNHL, sensorineural hearing loss.

Fig 2.

Overview of time from RT initiation to sensorineural hearing loss (SNHL) onset (Chang grade > 0) and progression (an increase in Chang grade from SNHL onset to the most recent evaluation). All 33 patients with SNHL were sorted by duration of follow-up. Patients with shorter follow-up periods were placed on the left side of the plot, and those with longer follow-up were placed on the right side. For all patients and ears in the plot, an arbitrary 100 days were added to the last evaluation so that the Chang grade at last evaluation can be visualized. L, left; R, right; RT, radiation therapy.

Fig 3.

(A) Kaplan-Meier plot showing the probability of not experiencing SNHL (Chang grade > 0) after exposure to RT (N = 235). (B) Kaplan-Meier plot showing the probability of not experiencing progression of hearing loss after SNHL onset (n = 33). RT, radiation therapy; SNHL, sensorineural hearing loss.

Fig A1.

Computed tomography image demonstrating how the cochlea was contoured within the temporal bone without additional margin.

Fig A2.

Scatter plot of cochlear radiation dose to the left and right ears of the 235 evaluable patients. Both, patients with bilateral sensorineural hearing loss (SNHL) (Chang grade > 0) (n = 13); left, patients with unilateral SNHL (Chang grade > 0) in left ear (n = 14); normal, patients with normal hearing (n = 202); right, patients with unilateral SNHL (Chang grade > 0) in right ear (n = 6).