Evaluation and analysis of risk factors of hearing impairment for nasopharyngeal carcinoma treated using intensity-modulated radiotherapy.

Abstract

Treating nasopharyngeal carcinoma (NPC) with radiotherapy frequently causes hearing impairment (HI). HI risk data haven't been evaluated quantitatively. This study aimed to analyze the probability of HI and sever HI (SHI), develop a nomogram to quantify individual prediction, and provide dose limitation suggestions. This single-center, retrospective study was conducted based on 588 adolescents and young adults with non-metastatic NPC treated using intensity modulated radiation therapy (IMRT) at Sun Yat-sen University Cancer Center between 2010 and 2016. A least absolute shrinkage and selection operator (LASSO) logistic regression model and univariate analysis were used to screen potential risk factors. The concordance index and a calibration curve evaluated the nomogram models' predictive ability, with bootstrap resampling validation. We analyzed 588 patients with NPC, with a median follow-up of 103.4 months. HI occurred in 39.5 % of patients, with 29.7 % experiencing SHI. Two factors were classified as precursors for HI (volume 45 Gy of the inner ear (IE_V45) and volume 50 Gy of the internal auditory canal (IAC_V50)), and IAC_min and IAC_V60 for SHI, respectively. Prognostic nomograms were developed to predict HI and SHI probabilities, showing excellent discriminative abilities (c-index values = 0.806 and 0.793, respectively). We also suggested IE_V45 < 50 % and/or IAC_V50 < 40 % as rational dose limitations for HI, and IAC_min < 44 Gy and/or the IAC_V60 < 40 % for SHI. Comprehensive analysis could predict the risk of HI and SHI in NPC after IMRT, proposing rational dose limitations and improving long-term quality of life.