Acoustic neuromas following childhood radiation treatment for benign conditions of the head and neck

Abstract

Childhood radiation exposure has been associated with an increased risk for developing several neoplasms, particularly benign and malignant thyroid tumors, but little is known about the risk of developing acoustic neuromas. The aim of this study was to confirm whether there is a risk for acoustic neuromas and, if so, to determine its magnitude and duration. We investigated the time trend and dose-response relationships for acoustic neuroma incidence in a cohort of 3,112 individuals who were irradiated as children between 1939 and 1962. Most of the patients were treated to reduce the size of their tonsils and adenoids and received substantial radiation exposure to the cerebellopontine angle, the site of acoustic neuromas. Forty-three patients developed benign acoustic neuromas, forty of them surgically resected, far in excess of what might be expected from data derived from brain tumor registries. The mean dose (+/-SD) to the cerebellopontine angle was 4.6 +/- 1.9 Gy. The relative risk per Gy was 1.14 (95% confidence interval 1.0-1.3). The earliest case occurred 20.4 years after exposure and the latest 55 years after exposure (mean 38.3 +/- 10.1 years). Our study provides support for an association between acoustic neuromas and childhood radiation exposure. Although acoustic neuromas are usually benign and often asymptomatic, many cause significant morbidity. Following childhood radiation exposure, they appear after a long latency and continue to occur many decades afterward. Any symptoms of an acoustic neuroma in a patient with a history of radiation to the head and neck area should be investigated carefully, and the threshold for employing imaging should be lowered.

Fig. 1

Distribution of estimated doses (Gy) to the cerebellopontine angle for the 3,112 individuals included in this study.

Fig. 2

Kaplan-Meier plot of acoustic neuroma-free survival from the time of radiation exposure. The intersecting vertical lines indicate the time points at which the population at risk decreases by 500 individuals.