Peternel Monika, Jenko Aljaša, Peterlin Primož, Petrovič Larisa, Strojan Primož, Plavc Gaber
Institute of Oncology, Department of Radiotherapy, Zaloška cesta 2, Ljubljana, Slovenia.
Faculty of Medicine, University of Ljubljana, Vrazov trg 2, Ljubljana, Slovenia.
Clin Transl Radiat Oncol. 2024 Feb 19;46:100751. doi: 10.1016/j.ctro.2024.100751. eCollection 2024 May.
Radiation-induced damage to the hippocampi can cause cognitive decline. International recommendations for nasopharyngeal cancer (NPC) radiotherapy (RT) lack specific guidelines for protecting the hippocampi. Our study evaluates if hippocampi-sparing (HS) RT in NPC ensures target coverage and meets recommended dose limits for other at-risk organs.
In a systematic literature review, we compared hippocampal D in conventional and HS RT plans. In an in silico dosimetric study, conventional and HS-VMAT plans were created for each patient, following international recommendations for OAR delineation, dose prioritization and acceptance criteria. We assessed the impact on neurocognitive function using a previously published normal tissue complication probability (NTCP) model.
In four previous studies (n = 79), researchers reduced D hippocampal radiation doses in HS plans compared to conventional RT on average from 24.9 Gy to 12.6 Gy.Among 12 NPC patients included in this in silico study, statistically significant differences between HS and conventional VMAT plans were observed in hippocampal EQD D (23.8 vs. 46.4 Gy), D (3.8 vs. 4.6 Gy), D (8.1 vs. 15.1 Gy), and D (8.3 vs. 15.8 Gy). PTV coverage and OAR doses were similar, with less homogeneous PTV coverage in HS plans (p = 0.038). This translated to a lower probability of memory decline in HS plans (interquartile range 15.8-29.6 %) compared to conventional plans (33.8-81.1 %) based on the NTCP model (p = 0.002).
Sparing the hippocampus in NPC RT is safe and feasible. Given the life expectancy of many NPC patients, their cognitive well-being must be paramount in radiotherapy planning.
辐射诱发的海马体损伤可导致认知功能下降。国际鼻咽癌（NPC）放射治疗（RT）指南缺乏保护海马体的具体指导原则。我们的研究评估了NPC的海马体保留（HS）RT是否能确保靶区覆盖，并满足其他危及器官的推荐剂量限制。
在一项系统的文献综述中，我们比较了传统RT计划和HS RT计划中的海马体剂量。在一项计算机模拟剂量学研究中，根据国际辐射危及器官（OAR）勾画、剂量优先级和接受标准的建议，为每位患者制定了传统和HS-VMAT计划。我们使用先前发表的正常组织并发症概率（NTCP）模型评估了对神经认知功能的影响。
在之前的四项研究（n = 79）中，研究人员发现，与传统RT相比，HS计划中的海马体辐射剂量平均从24.9 Gy降至12.6 Gy。在这项计算机模拟研究纳入的12例NPC患者中，HS和传统VMAT计划在海马体等效均匀剂量（EQD）（23.8 vs. 46.4 Gy）、D（3.8 vs. 4.6 Gy）、D（8.1 vs. 15.1 Gy）和D（8.3 vs. 15.8 Gy）方面存在统计学显著差异。计划靶体积（PTV）覆盖和OAR剂量相似，HS计划中的PTV覆盖均匀性较差（p = 0.038）。根据NTCP模型，这意味着HS计划中记忆衰退的概率低于传统计划（四分位间距15.8-29.6% 对比33.8-81.1%）（p = 0.002）。
NPC RT中保留海马体是安全可行的。鉴于许多NPC患者的预期寿命，他们的认知健康在放射治疗计划中必须是首要考虑因素。
