Nachankar Ankita, Schafasand Mansure, Hug Eugen, Martino Giovanna, Góra Joanna, Carlino Antonio, Stock Markus, Fossati Piero
ACMIT Gmbh, 2700 Wiener Neustadt, Austria.
Department of Radiation Oncology, MedAustron Ion Therapy Center, 2700 Wiener Neustadt, Austria.
Cancers (Basel). 2024 Mar 26;16(7):1284. doi: 10.3390/cancers16071284.
To minimize radiation-induced lumbosacral neuropathy (RILSN), we employed sacral-nerve-sparing optimized carbon-ion therapy strategy (SNSo-CIRT) in treating 35 patients with pelvic sarcomas/chordomas. Plans were optimized using Local Effect Model-I (LEM-I), prescribed D (median dose to HD-PTV) = 73.6 (70.4-76.8) Gy (RBE)/16 fractions. Sacral nerves were contoured between L5-S3 levels. D to 5% of sacral nerves-to-spare (outside HD-CTV) (D) were restricted to <69 Gy (RBE). The median follow-up was 25 months (range of 2-53). Three patients (9%) developed late RILSN (≥G3) after an average period of 8 months post-CIRT. The RILSN-free survival at 2 years was 91% (CI, 81-100). With SNSo-CIRT, D for sacral nerves-to-spare = 66.9 ± 1.9 Gy (RBE), maintaining D to 98% of HD-CTV (D) = 70 ± 3.6 Gy (RBE). Two-year OS and LC were 100% and 93% (CI, 84-100), respectively. LETd and D with modified-microdosimetric kinetic model (mMKM) were recomputed retrospectively. D and D were similar, but D-filtered-LETd was higher in sacral nerves-to-spare in patients with RILSN than those without. At D cutoff = 64 Gy (RBE), 2-year RILSN-free survival was 100% in patients with <12% of sacral nerves-to-spare voxels receiving LETd > 55 keV/µm than 75% (CI, 54-100) in those with ≥12% of voxels ( < 0.05). D-filtered-LETd holds promise for the SNSo-CIRT strategy but requires longer follow-up for validation.
为使放射性腰骶神经病变（RILSN）降至最低，我们采用保留骶神经的优化碳离子治疗策略（SNSo-CIRT）治疗35例盆腔肉瘤/脊索瘤患者。计划使用局部效应模型-I（LEM-I）进行优化，处方剂量D（高剂量计划靶区的中位剂量）=73.6（70.4-76.8）Gy（相对生物效应）/16次分割。在L5-S3水平之间勾勒出骶神经轮廓。将保留的5%骶神经（高剂量临床靶区外）的剂量（D）限制在<69 Gy（相对生物效应）。中位随访时间为25个月（范围2-53个月）。3例患者（9%）在碳离子治疗后平均8个月出现晚期RILSN（≥G3）。2年无RILSN生存率为91%（可信区间，81-100）。采用SNSo-CIRT时，保留骶神经的剂量D=66.9±1.9 Gy（相对生物效应），高剂量临床靶区98%的剂量（D）维持在70±3.6 Gy（相对生物效应）。2年总生存率和局部控制率分别为100%和93%（可信区间，84-100）。采用改良微剂量动力学模型（mMKM）对线性能量传递剂量（LETd）和剂量（D）进行回顾性重新计算。D和D相似，但RILSN患者保留骶神经的D过滤LETd高于无RILSN患者。在剂量截止值=64 Gy（相对生物效应）时，保留骶神经体素中<12%接受LETd>55 keV/µm的患者2年无RILSN生存率为100%，而≥12%体素的患者为75%（可信区间，54-100）（<0.05）。D过滤LETd对SNSo-CIRT策略有前景，但需要更长随访时间进行验证。
