OBJECTIVES Treatment-induced lesions represent a great challenge in neuro-oncology. The aims of this study were (i) to characterize treatment induced lesions in glioblastoma patients treated with chemoradiotherapy and heat-shock protein (HSP) vaccine and (ii) to evaluate the diagnostic accuracy of diffusion weighted imaging for differentiation between treatment-induced lesions and tumor progression. METHODS Twenty-seven patients with newly diagnosed glioblastoma treated with HSP vaccine and chemoradiotherapy were included. Serial magnetic resonance imaging evaluation was performed to detect treatment-induced lesions and assess their growth. Quantitative analysis of the apparent diffusion coefficient (ADC) was performed to discriminate treatment-induced lesions from tumor progression. Mann-Whitney U-test and receiver operating characteristic (ROC) curves were used for analysis. RESULTS Thirty-three percent of patients developed treatment-induced lesions. Five treatment-related lesions appeared between end of radiotherapy and the first vaccine administration; 4 lesions within the first 4 months from vaccine initiation and 1 at 3.5 years. Three patients with pathology proven treatment-induced lesions showed a biphasic growth pattern progressed shortly after. ADC ratio between the peripheral enhancing rim and central necrosis showed an accuracy of 0.84 (95% CI 0.63-1) for differentiation between progression and treatment-induced lesions. CONCLUSION Our findings do not support the iRANO recommendation of a 6-month time window in which progressive disease should not be declared after immunotherapy initiation. A biphasic growth pattern of pathologically proven treatment-induced lesions was associated with a dismal prognosis. The presence of lower ADC values in the central necrotic portion of the lesions compared to the enhancing rim shows high specificity for detection of treatment-induced lesions.

中文翻译：

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新诊断的胶质母细胞瘤患者接受化学放疗和热激蛋白疫苗治疗后，治疗引起的病变。

目的治疗引起的损伤代表了神经肿瘤学的巨大挑战。这项研究的目的是（i）表征接受放化疗和热休克蛋白（HSP）疫苗治疗的胶质母细胞瘤患者的治疗诱发的病变，以及（ii）评估弥散加权成像对治疗诱发的病变与肿瘤之间的区别的诊断准确性。肿瘤进展。方法纳入新诊断为胶质母细胞瘤的27例HSP疫苗和放化疗患者。进行了系列磁共振成像评估，以检测治疗引起的病变并评估其生长。进行了表观扩散系数（ADC）的定量分析，以区分治疗诱发的病变与肿瘤进展。使用Mann-Whitney U检验和接收器工作特性（ROC）曲线进行分析。结果33％的患者出现了治疗引起的病变。在放疗结束和首次接种疫苗之间出现了5种与治疗有关的病变。疫苗接种后的头4个月内有4个病灶，3.5年后1个病灶。经病理证实的三位患者经治疗诱发的病变显示不久后出现双相生长模式。周围增强边缘和中央坏死之间的ADC比率显示出0.84（95％CI 0.63-1）的准确度，可区分疾病进展与治疗引起的病变。结论我们的发现不支持iRANO建议的6个月时间窗，即免疫治疗开始后不应宣布进行性疾病。经病理证实的治疗引起的病变的双相生长模式与预后不良有关。与增强边缘相比，病变中央坏死部分中ADC值较低的存在表现出对检测治疗性病变的高度特异性。