King Martin T, Modlin Leslie, Million Lynn, Donaldson Sarah S, Gibbs Iris C, Choi Clara Y H, Soltys Scott G
Department of Radiation Oncology, Stanford University, Stanford, CA, USA
Department of Radiation Oncology, Stanford University, Stanford, CA, USA.
Technol Cancer Res Treat. 2016 Jun;15(3):472-9. doi: 10.1177/1533034615583406. Epub 2015 May 6.
Current craniospinal irradiation (CSI) protocols do not include the parotid gland as an organ at risk, potentially leading to late effects of xerostomia and secondary parotid malignancies. We analyzed the effect of CSI treatment parameters on parotid dose.
We retrospectively reviewed 50 consecutive patients treated with CSI to an intracranial dose >26 Gy. Parotid dose was compared to a Radiation Therapy Oncology Group (RTOG) dose constraint (at least 1 parotid with mean dose <26 Gy). The effects of CSI dose (≤24 Gy vs 24 Gy), volumetric-modulated arc therapy (VMAT) versus 3-dimensional (3D) CSI technique, boost dose (≤24 Gy vs 24 Gy), supratentorial versus infratentorial boost location, intensity-modulated radiation therapy (IMRT)-based versus 3D boost technique, supine versus prone position, and age on parotid dose were analyzed using multivariate regression analysis.
The RTOG parotid dose constraint was exceeded in 22 (44%) of 50 patients. On multivariate regression analysis, lower CSI dose and VMAT CSI technique were associated with reduced parotid dose for the CSI fields. For the boost fields, lower boost dose and supratentorial boost location were associated with lower parotid dose. All 5 patients who underwent VMAT CSI met dose constraints. Furthermore, for infratentorial lesions with a total (CSI plus boost) dose prescription dose >50 Gy (n = 24), 11 of 16 patients who received low-dose CSI (18-23.4 Gy) were able to meet dose constraints, when compared to only 2 of 8 patients who received high dose CSI (36 Gy).
Given the large number of patients exceeding the parotid dose constraint, the parotid gland should be considered an organ at risk. CSI dose de-escalation and IMRT-based CSI techniques may minimize the risk of xerostomia.
当前的全脑全脊髓照射（CSI）方案未将腮腺视为危险器官，这可能导致口干症和继发性腮腺恶性肿瘤等晚期效应。我们分析了CSI治疗参数对腮腺剂量的影响。
我们回顾性分析了50例接受颅内剂量>26 Gy的CSI治疗的连续患者。将腮腺剂量与放射治疗肿瘤学组（RTOG）的剂量限制（至少1个腮腺平均剂量<26 Gy）进行比较。使用多因素回归分析，分析了CSI剂量（≤24 Gy与24 Gy）、容积调强弧形放疗（VMAT）与三维（3D）CSI技术、推量剂量（≤24 Gy与24 Gy）、幕上与幕下推量位置、基于调强放射治疗（IMRT）的推量技术与3D推量技术、仰卧位与俯卧位以及年龄对腮腺剂量的影响。
50例患者中有22例（44%）超过了RTOG腮腺剂量限制。多因素回归分析显示，较低的CSI剂量和VMAT CSI技术与CSI野腮腺剂量降低相关。对于推量野，较低的推量剂量和幕上推量位置与较低的腮腺剂量相关。所有5例接受VMAT CSI的患者均符合剂量限制。此外，对于总（CSI加推量）剂量处方剂量>50 Gy的幕下病变（n = 24），接受低剂量CSI（18 - 23.4 Gy）的16例患者中有11例能够符合剂量限制，而接受高剂量CSI（36 Gy）的8例患者中只有2例符合。
鉴于大量患者超过腮腺剂量限制，应将腮腺视为危险器官。CSI剂量降低和基于IMRT的CSI技术可能会使口干症风险降至最低。
