Hypofractionation results in reduced tumor cell kill compared to conventional fractionation for tumors with regions of hypoxia.
Hypofractionation results in reduced tumor cell kill compared to conventional fractionation for tumors with regions of hypoxia.
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DOI：
10.1016/j.ijrobp.2010.10.007
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发表时间：
2011-03-15
影响因子：
7
通讯作者：
Brown, J. Martin
中科院分区：
文献类型：
--
作者：
Carlson, David J.;Keall, Paul J.;Loo, Billy W., Jr.;Chen, Zhe J.;Brown, J. Martin
在许多人类癌症中都观察到肿瘤缺氧，并且与放射治疗的治疗失败有关。本研究的目的是在假设肿瘤氧合分布真实的情况下，量化不同放射分割方案对肿瘤细胞杀伤的影响。肿瘤细胞群中氧分压的概率密度函数被量化为距毛细血管壁的径向距离的函数。确定用于细胞杀伤的相应缺氧减少因子（HRF）。由最大抵抗细胞、中等缺氧水平的细胞和含氧量正常细胞组成的肿瘤的存活分数被计算为含氧量正常条件下等效肿瘤生物有效剂量的每个分数的剂量的函数。缺氧随着距血管距离的增加而增加，导致典型放射治疗分割方案的肿瘤细胞杀伤力在 130 μm 距离内减少 105 倍。对于头颈癌和前列腺癌，随着每部分的剂量分别从 2 Gy 增加到 24 Gy 和从 2 Gy 增加到 18 Gy，在整个治疗过程中杀死的肿瘤克隆原的分数最多减少约 103 倍。由于肿瘤缺氧，与标准分割相比，放疗方案的大分割可导致肿瘤细胞杀伤显着减少。使用不考虑肿瘤缺氧的形式计算替代分数时，可能会出现较大误差。
Tumor hypoxia has been observed in many human cancers and is associated with treatment failure in radiation therapy. The purpose of this study is to quantify the effect of different radiation fractionation schemes on tumor cell killing assuming a realistic distribution of tumor oxygenation. A probability density function for the partial pressure of oxygen in a tumor cell population is quantified as a function of radial distance from the capillary wall. Corresponding hypoxia reduction factors (HRFs) for cell killing are determined. The surviving fraction of a tumor consisting of maximally resistant cells, cells at intermediate levels of hypoxia, and normoxic cells is calculated as a function of dose per fraction for an equivalent tumor biological effective dose under normoxic conditions. Increasing hypoxia as a function of distance from blood vessels results in a decrease in tumor cell killing for a typical radiotherapy fractionation scheme by a factor of 105 over a distance of 130 μm. For head and neck and prostate cancer, the fraction of tumor clonogens killed over a full treatment course decreases by up to a factor of ~ 103 as the dose per fraction is increased from 2 to 24 Gy and from 2 to 18 Gy, respectively. Hypofractionation of a radiotherapy regimen can result in a significant decrease in tumor cell killing compared to standard fractionation as a result of tumor hypoxia. There is a potential for large errors when calculating alternate fractionations using formalisms that do not account for tumor hypoxia.
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DOI：
10.1016/s0360-3016(96)00579-2
发表时间：
1997-03-15
影响因子：
7
作者：
Haustermans, KMG;Hofland, I;Fowler, JF
通讯作者：
Fowler, JF
影响因子：
3.4
作者：
Fowler, J. F.
通讯作者：
Fowler, J. F.
DOI：
10.1016/s0360-3016(02)04503-0
发表时间：
2003-06-01
影响因子：
7
作者：
Le, QT;Kovacs, MS;Brown, JM
通讯作者：
Brown, JM
影响因子：
3.4
作者：
KOCH, CJ;STOBBE, CC;BUMP, EA
通讯作者：
BUMP, EA
影响因子：
5.7
作者：
Drzymala, R. E.;Wasserman, T. H.;Souhami, L.
通讯作者：
Souhami, L.