The University of Texas MD Anderson Cancer Center, Houston, Texas, USA.
Mayo Clinic, Rochester, Minnesota, USA.
Neuro Oncol. 2019 May 6;21(5):686-695. doi: 10.1093/neuonc/noz042.
Pseudoprogression (PsP) is a recognized phenomenon after radiotherapy (RT) for high-grade glioma but is poorly characterized for low-grade glioma (LGG). We sought to characterize PsP for pediatric LGG patients treated with RT, with particular focus on the role of RT modality using photon-based intensity-modulated RT (IMRT) or proton beam therapy (PBT).
Serial MRI scans from 83 pediatric LGG patients managed at 2 institutions between 1998 and 2017 were evaluated. PsP was scored when a progressive lesion subsequently decreased or stabilized for at least a year without therapy.
Thirty-two patients (39%) were treated with IMRT, and 51 (61%) were treated with PBT. Median RT dose for the cohort was 50.4 Gy(RBE) (range, 45-59.4 Gy[RBE]). PsP was identified in 31 patients (37%), including 8/32 IMRT patients (25%) and 23/51 PBT patients (45%). PBT patients were significantly more likely to have post-RT enlargement (hazard ratio [HR] 2.15, 95% CI: 1.06-4.38, P = 0.048). RT dose >50.4 Gy(RBE) similarly predicted higher rates of PsP (HR 2.61, 95% CI: 1.20-5.68, P = 0.016). Multivariable analysis confirmed the independent effects of RT modality (P = 0.03) and RT dose (P = 0.01) on PsP incidence. Local progression occurred in 10 patients: 7 IMRT patients (22%) and 3 PBT patients (6%), with a trend toward improved local control for PBT patients (HR 0.34, 95% CI: 0.10-1.18, P = 0.099).
These data highlight substantial rates of PsP among pediatric LGG patients, particularly those treated with PBT. PsP should be considered when assessing response to RT in LGG patients within the first year after RT.
假性进展（PsP）是高级别胶质瘤放疗后一种公认的现象，但在低级别胶质瘤（LGG）中特征描述较差。我们旨在研究接受放疗的儿科 LGG 患者的 PsP，特别关注使用光子调强放疗（IMRT）或质子束治疗（PBT）的放疗方式的作用。
对 1998 年至 2017 年在 2 个机构接受治疗的 83 例儿科 LGG 患者的连续 MRI 扫描进行评估。当病变进展后至少 1 年没有治疗而出现病变减少或稳定时，将其评分 PsP。
32 例患者（39%）接受 IMRT 治疗，51 例患者（61%）接受 PBT 治疗。该队列的中位放疗剂量为 50.4 Gy（RBE）（范围，45-59.4 Gy[RBE]）。31 例患者（37%）出现 PsP，其中 8 例/32 例 IMRT 患者（25%）和 23 例/51 例 PBT 患者（45%）。PBT 患者在放疗后发生扩大的可能性明显更高（风险比[HR]2.15，95%CI：1.06-4.38，P=0.048）。放疗剂量＞50.4 Gy（RBE）同样预测更高的 PsP 发生率（HR 2.61，95%CI：1.20-5.68，P=0.016）。多变量分析证实了放疗方式（P=0.03）和放疗剂量（P=0.01）对 PsP 发生率的独立影响。10 例患者发生局部进展：7 例 IMRT 患者（22%）和 3 例 PBT 患者（6%），PBT 患者的局部控制率有改善趋势（HR 0.34，95%CI：0.10-1.18，P=0.099）。
这些数据突出了儿科 LGG 患者中 PsP 的发生率较高，尤其是接受 PBT 治疗的患者。在放疗后第一年评估 LGG 患者的放疗反应时，应考虑 PsP。
