Gallagher Kyle J, Youssef Bassem, Georges Rola, Mahajan Anita, Feghali Joelle Ann, Nabha Racile, Ayoub Zeina, Jalbout Wassim, Taddei Phillip J
Oregon Health and Science University, Portland, OR, USA.
Oregon State University, Corvallis, OR, USA.
Int J Part Ther. 2021 Feb 17;7(4):1-10. doi: 10.14338/IJPT-20-00041.1. eCollection 2021 Spring.
To test our hypothesis that, for young children with intracranial tumors, proton radiotherapy in a high-income country does not reduce the risk of a fatal subsequent malignant neoplasm (SMN) compared with photon radiotherapy in low- and middle-income countries.
We retrospectively selected 9 pediatric patients with low-grade brain tumors who were treated with 3-dimensional conformal radiation therapy in low- and middle-income countries. Images and contours were deidentified and transferred to a high-income country proton therapy center. Clinically commissioned treatment planning systems of each academic hospital were used to calculate absorbed dose from the therapeutic fields. After fusing supplemental computational phantoms to the patients' anatomies, models from the literature were applied to calculate stray radiation doses. Equivalent doses were determined in organs and tissues at risk of SMNs, and the lifetime attributable risk of SMN mortality () was predicted using a dose-effect model. Our hypothesis test was based on the average of the ratios of from proton therapy to that of photon therapy ()(H: = 1; H : < 1).
Proton therapy reduced the equivalent dose in organs at risk for SMNs and compared with photon therapy for which the for the cohort was 0.69 ± 0.10, resulting in the rejection of H ( < .001, α = 0.05). We observed that the younger children in the cohort (2-4 years old) were at a factor of approximately 2.5 higher compared with the older children (8-12 years old).
Our findings suggest that proton radiotherapy has the strong potential of reducing the risk of fatal SMNs in pediatric patients with intracranial tumors if it were made available globally.
验证我们的假设，即对于患有颅内肿瘤的幼儿，在高收入国家进行质子放疗与在低收入和中等收入国家进行光子放疗相比，不会降低后续发生致命性继发恶性肿瘤（SMN）的风险。
我们回顾性选择了9例在低收入和中等收入国家接受三维适形放射治疗的低级别脑肿瘤儿科患者。对图像和轮廓进行去识别处理后，将其转至一家高收入国家的质子治疗中心。使用各学术医院临床委托的治疗计划系统来计算治疗野的吸收剂量。在将补充的计算体模与患者解剖结构融合后，应用文献中的模型来计算散在辐射剂量。确定有发生SMN风险的器官和组织中的当量剂量，并使用剂量效应模型预测SMN死亡的终生归因风险（）。我们的假设检验基于质子治疗与光子治疗的（）比值的平均值（原假设：= 1；备择假设：< 1）。
与光子治疗相比，质子治疗降低了有发生SMN风险的器官中的当量剂量，该队列的为0.69±0.10，导致原假设被拒绝（<0.001，α = 0.05）。我们观察到，该队列中年龄较小的儿童（2 - 4岁）发生的风险比年龄较大的儿童（8 - 12岁）高约2.5倍。
我们的研究结果表明，如果质子放疗能在全球范围内普及，那么它在降低颅内肿瘤儿科患者发生致命性SMN风险方面具有很大潜力。
