RONC-09. The comparison of dosimetric parameters for predicting radiation-induced cataract in pediatric patients

OBJECTIVE: The lens dose constraint for pediatric patients was still unknown due to conflicting data of dosimetric parameter. The aim of this study was to compare predictive ability for radiation-induced cataract between the maximum point dose of lens (Lens Dmax) ≥7 Gy, lens mean dose (Lens Dmean) ≥7 Gy, Lens Dmax ≥10 Gy, and Lens Dmean ≥10 Gy. METHOD: Patients 3-18 years received cranial irradiation or radiation therapy at head and neck area with three-dimentional conformal radiation therapy (3DCRT), intensity modulated radiation therapy (IMRT), or volumetric modulated arc therapy (VMAT) between 2010 and 2019 at our institute were included. Patients who have no eye exam before radiation or within 6 months of radiation (baseline) and/or have no follow-up eye examination after complete radiation >6 months (follow-up) were excluded. Receiver operating characteristic (ROC) curves were used to identify the dosimetric parameter of potential predictors and to access their predictability. Univariate and multivariate analyses were performed using cox regression analysis to identify correlation between potential factors and cataract. RESULTS: Sixty-three patients (122 eyes) were analyzed. Cataracts were detected in 14 eyes (11.5%). The median follow-up time was 4 years (range 0.5-10 years). The median time to develop cataract was 2.5 years (range 0.3-7 years). Three (21.4%) patients developed cataract grade ≥3. Lens Dmean ≥10 Gy had highest predictive ability for predicting radiation-induced cataract in pediatric patients. The area under the ROC curve (AUC) were 0.591 for Dmax ≥ 7 Gy, 0.597 for Dmean ≥ 7 Gy, 0.642 for Dmax ≥ 10 Gy, and 0.698 for Dmean ≥ 10 Gy. Univariate analysis showed significant effect of age, diagnosis, and Lens Dmean on cataract formation. On multivariate analysis, cataract remained significantly predicted by diagnosis and Lens Dmean. CONCLUSION: Lens Dmean ≥10 Gy had highest predictive ability for predicting radiation-induced cataract in pediatric patients.