Lindblom Emely Kjellsson, Dasu Alexandru, Toma-Dasu Iuliana
Medical Radiation Physics, Department of Physics, Stockholm University, Stockholm, Sweden
Department of Medical and Health Sciences, Linköping University, Linköping, Sweden.
Anticancer Res. 2019 May;39(5):2337-2340. doi: 10.21873/anticanres.13350.
BACKGROUND/AIM: This study investigated the impact of temporary vascular collapse on tumour control probability (TCP) in stereotactic body radiotherapy (SBRT), taking into account different radiosensitivities of chronically and acutely hypoxic cells.
Three-dimensional tumours with heterogeneous oxygenation were simulated assuming different fractions of collapsed vessels at every treatment fraction. The modelled tumours contained a chronically hypoxic subvolume of 30-60% of the tumour diameter, and a hypoxic fraction ≤5 mm Hg of 30-50%. The rest of the tumours were well-oxygenated at the start of the simulated treatment.
For all simulated cases, the largest reduction in TCP from 97% to 2% was found in a tumour with a small chronically hypoxic core treated with 60 Gy in eight fractions and assuming a treatment-induced vascular collapse of 35% in the well-oxygenated region.
The timing of SBRT fractions should be considered together with the tumour oxygenation to avoid loss of TCP in SBRT.
背景/目的：本研究探讨了立体定向体部放疗（SBRT）中暂时性血管塌陷对肿瘤控制概率（TCP）的影响，同时考虑了慢性和急性缺氧细胞的不同放射敏感性。
模拟了具有异质性氧合的三维肿瘤，假设每次治疗分次时血管塌陷的比例不同。模拟的肿瘤包含一个慢性缺氧亚体积，其直径占肿瘤的30% - 60%，以及一个氧分压≤5 mmHg的缺氧部分，占30% - 50%。在模拟治疗开始时，其余肿瘤为充分氧合。
对于所有模拟病例，在一个具有小的慢性缺氧核心的肿瘤中，发现TCP最大降幅从97%降至2%，该肿瘤接受8次分割共60 Gy的治疗，并假设在充分氧合区域治疗诱导的血管塌陷率为35%。
SBRT分次的时间安排应与肿瘤氧合情况一并考虑，以避免SBRT中TCP的损失。
