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Evolution and Dosimetric Analysis of MRI-detected Brainstem Injury Following Intensity Modulated Radiotherapy in Nasopharyngeal Carcinoma.
Int J Radiat Oncol Biol Phys. 2019 May 07;:
Authors: Huang XD, Li YC, Chen FP, Zheng WH, Zhou GQ, Lin L, Hu J, He WJ, Zhang LL, Kou J, Ma J, Zhang WD, Qi ZY, Sun Y
Abstract
PURPOSE: To evaluate the evolution of radiation-induced brainstem injury (BSI) in nasopharyngeal-carcinoma (NPC) patients treated with intensity-modulated radiotherapy (IMRT) and to identify the critical dosimetric predictors of BSI.
MATERIALS AND METHODS: A total of 6288 NPC patients treated with IMRT between 2009 and 2015 were retrospectively reviewed. Among these 6288 patients 24 had radiation-induced BSI, manifesting as edematous lesions (ELs) and contrast-enhanced lesions (CLs) on magnetic resonance imaging (MRI). Latency, symptoms, and evolution of BSI were assessed. Critical dosimetric predictors of BSI were identified using a penalized regression model with performance evaluated by receiver operating curve (ROC) analysis.
RESULTS: Median BSI latency was 14.5 months (range, 7.6-37.5 months), and 37.5% (9/24) of patients were clinically symptomatic. ELs and CLs were both present in all patients. Necrosis was significantly more common in larger CLs (P = 0.007). After median follow-up of 12.5 months, 13/24 (54.2%) patients had complete remission and 5/24 (20.8%) patients had partial remission. Remission was unaffected by whether or not symptomatic treatment was given. Dmax was identified as the critical predictor of BSI (area under the ROC curve = 0.898), with the optimal cutoff equivalent dose in 2-Gy fractions (D2) being 67.4 Gy (sensitivity = 0.833, 20/24; specificity = 0.835, 5234/6264). Patients with Dmax ≥67.4 Gy (D2) were significantly more likely to develop BSI (odds ratio = 25.29, 95% CI: 8.63-74.14; P < 0.001) than those with Dmax <67.4 Gy (D2).
CONCLUSIONS: In NPC patients treated with IMRT BSI generally tends to improve over time. Dmax = 67.4 Gy (D2) appears to be the dose constraint for brainstem, potentially providing clinicians with greater choice and flexibility when balancing the tumor target coverage and brainstem protection. Further studies are needed to validate our findings.
PURPOSE: To evaluate the evolution of radiation-induced brainstem injury (BSI) in nasopharyngeal-carcinoma (NPC) patients treated with intensity-modulated radiotherapy (IMRT) and to identify the critical dosimetric predictors of BSI.
MATERIALS AND METHODS: A total of 6288 NPC patients treated with IMRT between 2009 and 2015 were retrospectively reviewed. Among these 6288 patients 24 had radiation-induced BSI, manifesting as edematous lesions (ELs) and contrast-enhanced lesions (CLs) on magnetic resonance imaging (MRI). Latency, symptoms, and evolution of BSI were assessed. Critical dosimetric predictors of BSI were identified using a penalized regression model with performance evaluated by receiver operating curve (ROC) analysis.
RESULTS: Median BSI latency was 14.5 months (range, 7.6-37.5 months), and 37.5% (9/24) of patients were clinically symptomatic. ELs and CLs were both present in all patients. Necrosis was significantly more common in larger CLs (P = 0.007). After median follow-up of 12.5 months, 13/24 (54.2%) patients had complete remission and 5/24 (20.8%) patients had partial remission. Remission was unaffected by whether or not symptomatic treatment was given. Dmax was identified as the critical predictor of BSI (area under the ROC curve = 0.898), with the optimal cutoff equivalent dose in 2-Gy fractions (D2) being 67.4 Gy (sensitivity = 0.833, 20/24; specificity = 0.835, 5234/6264). Patients with Dmax ≥67.4 Gy (D2) were significantly more likely to develop BSI (odds ratio = 25.29, 95% CI: 8.63-74.14; P < 0.001) than those with Dmax <67.4 Gy (D2).
CONCLUSIONS: In NPC patients treated with IMRT BSI generally tends to improve over time. Dmax = 67.4 Gy (D2) appears to be the dose constraint for brainstem, potentially providing clinicians with greater choice and flexibility when balancing the tumor target coverage and brainstem protection. Further studies are needed to validate our findings.
PMID: 31075310 [PubMed - as supplied by publisher]
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