Specific growth rate versus doubling time for quantitative characterization of tumor growth rate
Specific growth rate versus doubling time for quantitative characterization of tumor growth rate
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DOI：
10.1158/0008-5472.can-06-3822
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发表时间：
2007-04-15
期刊：
影响因子：
11.2
通讯作者：
Bernhardt, Peter
中科院分区：
文献类型：
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作者：
Mehrara, Esmaeil;Forssell-Aronsson, Eva;Bernhardt, Peter
倍增时间（DT）广泛用于定量肿瘤生长速率。DT通常由两个体积估计值确定，测量时间间隔与DT相当或更短。临床数据显示，患者DT的频率分布是正偏态的，与平均DT相比，有一些非常长的DT值。生长速率也可以使用比生长速率（SGR; %/d）定量，等于In 2/DT。这项工作的目的是比较DT和SGR作为增长率变量。计算机模拟肿瘤的生长速率计算，DT为100天，测量时间间隔为1至200天，体积估计不确定性为5%至20%。确定生长率变量并与之前发表的临床数据进行比较。该研究表明，DT不是肿瘤生长速率的合适变量，因为（a）对于短测量时间间隔或高体积不确定性，平均DT可能高估或低估平均生长速率;（B）如果连续估计的体积相等，则不定义DT;（c）DT的不对称频率分布使其不适用于常见的统计检验。相比之下，平均SGR及其等效DT给出了平均生长速率的正确值，SGR定义为所有肿瘤体积变化，并且具有对称的频率分布。SGR在讨论例如肿瘤内的生长分数、细胞损失率和生长速率异质性时也更准确。因此，应使用SGR而不是DT来量化肿瘤生长速率。
Doubling time (DT) is widely used for quantification of tumor growth rate. DT is usually determined from two volume estimations with measurement time intervals comparable with or shorter than DT. Clinical data show that the frequency distribution of DT in patients is positively skewed, with some very long DT values compared with the average DT. Growth rate can also be quantified using specific growth rate (SGR; %/d), equal to In2/DT. The aim of this work was to compare DT and SGR as growth rate variables. Growth rate calculations were computer simulated for a tumor with DT of 100 days, measurement time interval of 1 to 200 days, and volume estimation uncertainty of 5% to 20%. Growth rate variables were determined and compared for previously published clinical data. The study showed that DT is not a suitable variable for tumor growth rate because (a) for short measurement time intervals, or high volume uncertainties, mean DT can either overestimate or underestimate the average growth rate; (b) DT is not defined if the consecutively estimated volumes are equal; and (c) the asymmetrical frequency distribution of DT makes it unsuitable for common statistical testing. In contrast, mean SGR and its equivalent DT give the correct values for average growth rate, SGR is defined for all tumor volume changes, and it has a symmetrical frequency distribution. SGR is also more accurate to use when discussing, for example, growth fraction, cell loss rate, and growth rate heterogeneities within the tumor. SGR should thus be used, instead of DT, to quantify tumor growth rate.