ESTRO 2021 Abstract Book

S281

ESTRO 2021

Above: 3-year local control. Below: 3-year survival with preserved nose. Log-rank test for significance. Abbreviations: BT, brachytherapy; EBRT, external beam radiotherapy. Table 1: multivariable Cox regression analysis of survival endpoints

Conclusion In this largest-to-date multicenter study on T1-T2 CNV, BT attains higher LC, nose preservation rates and ultimately SPN compared with EBRT. Late radiation sequelae, particularly ulcers, occurred more often after BT, but were transient in 50% of cases. Considering these results, BT can be recommended as first-line treatment for T1-T2 CNV. PH-0383 Hearing loss in nasopharyngeal carcinoma survivors in modern era − Effect of radiation and cisplatin P.L. Yip 1 , K.C.J. Mok 2 , A.C.L. Wong 3 , F.C.S. Wong 4 , K.W. Yeung 3 , S.F. Lee 4 1 Tuen Mun Hospital , Department of Clinical Oncology, Hong Kong, Hong Kong (SAR) China; 2 Tuen Mun Hospital , Department of Otorhinolaryngology, Hong Kong, Hong Kong (SAR) China; 3 Tuen Mun Hospital, Department of Otorhinolaryngology, Hong Kong, Hong Kong (SAR) China; 4 Tuen Mun Hospital, Department of Clinical Oncology, Hong Kong, Hong Kong (SAR) China Purpose or Objective Hearing loss is a debilitating side effect in nasopharyngeal carcinoma (NPC) survivors after radiation-based treatment. Higher cisplatin dose was increasingly advocated in current treatment paradigm. We investigate the impact of cochlear radiation dose and cisplatin on early and late sensorineural hearing loss (SNHL) in patients treated with radiotherapy alone, concurrent chemoirradiation (cCRT) and induction chemotherapy followed by cCRT (iCRT), in intensity-modulated radiotherapy (IMRT) era. Materials and Methods Ninety-nine NPC patients treated with IMRT from 2014-2016 were retrospectively studied. Pure tone audiometry was performed at baseline and follow-up. SNHL was evaluated with bone conduction threshold change from baseline (BCT∆) at 0.5kHz, 1kHz, 2kHz and 4kHz. Significant SNHL was defined as BCT∆≥15dB. Cochlear radiation dose and cisplatin dose were analyzed in multivariable analysis, adjusting for important clinical predictors, on early (<12 months) and late (≥24 months) SNHL. Results Of 190 eligible ears, cochlear Dmean significantly predicted early low frequency (LF) BCT∆ 0.5Hz (B=0.002,