Department of Radiation Oncology, Academic Medical Center, University of Amsterdam, Meibergdreef 9, 1105 AZ, Amsterdam, The Netherlands.
Department of Radiation Oncology, The Netherlands Cancer Institute-Antoni van Leeuwenhoek, Plesmanlaan 121, 1066 CX, Amsterdam, The Netherlands.
Strahlenther Onkol. 2018 Mar;194(3):255-263. doi: 10.1007/s00066-017-1224-8. Epub 2017 Nov 3.
The aim of the study was to investigate the potential clinical benefit from both target tailoring by excluding the tumour-free proximal part of the uterus during image-guided adaptive radiotherapy (IGART) and improved dose conformity based on intensity-modulated proton therapy (IMPT).
The study included planning CTs from 11 previously treated patients with cervical cancer with a >4-cm tumour-free part of the proximal uterus on diagnostic magnetic resonance imaging (MRI). IGART and robustly optimised IMPT plans were generated for both conventional target volumes and for MRI-based target tailoring (where the non-invaded proximal part of the uterus was excluded), yielding four treatment plans per patient. For each plan, the V, V, V and D for bladder, sigmoid, rectum and bowel bag were compared, and the normal tissue complication probability (NTCP) for ≥grade 2 acute small bowel toxicity was calculated.
Both IMPT and MRI-based target tailoring resulted in significant reductions in V, V, V and D for bladder and small bowel. IMPT reduced the NTCP for small bowel toxicity from 25% to 18%; this was further reduced to 9% when combined with MRI-based target tailoring. In four of the 11 patients (36%), NTCP reductions of >10% were estimated by IMPT, and in six of the 11 patients (55%) when combined with MRI-based target tailoring. This >10% NTCP reduction was expected if the V for bowel bag was >275 cm and >200 cm, respectively, during standard IGART alone.
In patients with cervical cancer, both proton therapy and MRI-based target tailoring lead to a significant reduction in the dose to surrounding organs at risk and small bowel toxicity.
本研究旨在探讨通过在图像引导自适应放疗（IGART）中排除子宫无肿瘤的近段和基于调强质子治疗（IMPT）的提高剂量适形性，从靶向治疗方面获得潜在的临床获益。
该研究纳入了 11 例先前接受治疗的宫颈癌患者的计划 CT，这些患者在诊断性磁共振成像（MRI）上有>4cm 无肿瘤的子宫近段。为传统靶区和基于 MRI 的靶区定制（排除未侵犯的子宫近段）生成了 IGART 和稳健优化的 IMPT 计划，每位患者生成了 4 个治疗计划。对于每个计划，比较了膀胱、乙状结肠、直肠和肠袋的 V、V、V 和 D，并计算了≥2 级急性小肠毒性的正常组织并发症概率（NTCP）。
IMPT 和基于 MRI 的靶区定制都显著降低了膀胱和小肠的 V、V、V 和 D。IMPT 将小肠毒性的 NTCP 从 25%降低至 18%；当与基于 MRI 的靶区定制相结合时，进一步降低至 9%。在 11 名患者中的 4 名（36%）中，IMPT 估计 NTCP 降低>10%，在 11 名患者中的 6 名（55%）中，当与基于 MRI 的靶区定制相结合时，NTCP 降低>10%。如果在标准的 IGART 中，肠袋的 V 分别大于 275cm 和 200cm，则预计会有超过 10%的 NTCP 降低。
在宫颈癌患者中，质子治疗和基于 MRI 的靶区定制都显著降低了周围危及器官和小肠毒性的剂量。
