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首页> 外文期刊>Journal of Theoretical Biology >Development of generalized time-dependent TCP model and the investigation of the effect of repopulation and weekend breaks in fractionated external beam therapy
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Development of generalized time-dependent TCP model and the investigation of the effect of repopulation and weekend breaks in fractionated external beam therapy

机译：广义时间依赖的TCP模型的发展与调查分馏外束治疗中的重新流和周末突破的影响

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We developed a tumor control probability (TCP) model that incorporates variable time intervals between fractions and a kick-off time (T-k) for radiation-induced accelerated tumor proliferation. The resulting Lee-Rosen model, TCPLR, was used to compute TCPs for treatment courses with and without weekend treatment for tumors with different proliferation rates - slow (prostate), moderate (breast), and rapid (head and neck). TCPs were computed using ideal uniform dose distributions and actual patient plans. The doses for the uniform plans were the mean doses for the prostate and breast cases and the minimum tumor dose for the head and neck case. The TCPLR model predictions agreed with expectations that TCP increases with increasing T-k in all cases. For standard fractionation, as T-k increased from 0 to 4 weeks, TCP increased for the patient distributions by 74.7% for the head and neck cancer, by 6.2% for the breast cancer, and by 2.4% for the prostate cancers. For the uniform dose distributions, the increases were 79.2%, 5.7%, and 2.3%, respectively. TCP increased as the number of weekend breaks decreased. The effect of weekend breaks decreased as the tumor proliferation rate decreased. For the head and neck tumor, notable decreases in TCP of 6.0% (uniform dose distribution) and 6.8% (actual plan dose distribution) were observed with Friday starts compared to Monday starts for the standard 5 fx/wk schedule (11 = 4 wk). The 7 fx/wk schedule produced increases in TCP of 17.0% and 20.5% for the uniform and patient dose distributions, respectively, compared to the standard schedule. For the breast cancer, starting the 5 fx/wk schedule on Friday decreased the TCP by 0.2% (T-k = 4 wk) compared to a Monday start. The 7 fx/wk schedule produced increases of 0.3% and 0.4% in TCP compared to the standard schedule for the uniform and patient dose distributions, respectively (T-k = 4 wk). For the prostate cancer, the change in TCP for 5 fx/wk schedules starting on different days was 0.1%. The 7 fx/wk schedule increased TCP by 0.8% compared to the standard schedule (T-k = 4 wk). TCP values for the uniform dose distributions for the standard schedule (T-k = 4 wk) agreed with the TCP values for the actual dose distributions within 4.5% for the head and neck tumor and within 0.2% for the breast and prostate tumors. This good agreement suggests that the doses chosen for the uniform dose distributions were good approximations to the clinical doses. The results for head and neck tumors support, in part, the current practice of hyperfractionated/accelerated radiotherapy. They also suggest that shortening the overall treatment time for conventional fractions by eliminating weekend breaks might be beneficial. The predicted effect on TCP of the various schedules studied was insignificant for prostate and breast tumors, suggesting that a weekend treatment might not be necessary for patients starting radiotherapy on a Friday. There is significant uncertainty in the values of the model parameters chosen for these calculations, and no consideration was given to the potential effects of these various schedules on normal tissues. (C) 2020 Elsevier Ltd. All rights reserved.
机译：我们开发了一个肿瘤控制概率（TCP）模型，该模型包含了分数之间的可变时间间隔和辐射诱导加速肿瘤增殖的启动时间（T-k）。由此产生的Lee-Rosen模型（TCPLR）用于计算不同增殖率肿瘤（缓慢（前列腺）、中度（乳腺）和快速（头颈部）周末治疗前后治疗疗程的TCP。使用理想的均匀剂量分布和实际患者计划计算TCP。统一计划的剂量为前列腺和乳腺病例的平均剂量，以及头部和颈部病例的最小肿瘤剂量。TCPLR模型的预测与预期一致，即在所有情况下，TCP都随着T-k的增加而增加。对于标准分级，随着T-k从0周增加到4周，头颈癌患者分布的TCP增加了74.7%，乳腺癌增加了6.2%，前列腺癌增加了2.4%。对于均匀剂量分布，增加率分别为79.2%、5.7%和2.3%。TCP随着周末休息次数的减少而增加。周末休息的影响随着肿瘤增殖率的降低而降低。对于头颈部肿瘤，与标准5 fx/wk计划（11=4 wk）的周一开始相比，周五开始时的TCP显著降低6.0%（均匀剂量分布）和6.8%（实际计划剂量分布）。与标准计划相比，7 fx/wk计划使均匀剂量分布和患者剂量分布的TCP分别增加17.0%和20.5%。对于乳腺癌患者，与周一开始相比，周五开始5次/wk的治疗计划将TCP降低了0.2%（T-k=4周）。与均匀剂量分布和患者剂量分布（T-k=4周）的标准方案相比，7 fx/wk方案在TCP中分别增加了0.3%和0.4%。对于前列腺癌患者，从不同的日期开始，每工作周5次的TCP变化为0.1%。与标准时间表（T-k=4周）相比，7 fx/周时间表将TCP增加了0.8%。标准计划（T-k=4周）的均匀剂量分布的TCP值与实际剂量分布的TCP值一致，头颈部肿瘤的TCP值在4.5%以内，乳腺和前列腺肿瘤的TCP值在0.2%以内。这种良好的一致性表明，为均匀剂量分布选择的剂量与临床剂量非常接近。头颈部肿瘤的研究结果在一定程度上支持了目前超分割/加速放射治疗的实践。他们还建议，通过取消周末休息来缩短常规组分的整体治疗时间可能是有益的。对于前列腺和乳腺肿瘤而言，研究中的各种治疗方案对TCP的预测效果并不显著，这表明对于在周五开始放疗的患者，周末治疗可能不是必要的。为这些计算选择的模型参数值存在很大的不确定性，并且没有考虑这些不同计划对正常组织的潜在影响。（C） 2020爱思唯尔有限公司版权所有。

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