Stuschke M, Budach V, Bamberg M, Budach W
Department of Radiotherapy, University of Essen, Federal Republic of Germany.
Radiat Res. 1990 May;122(2):172-80.
Growth delay times of experimental tumors after subcurative therapy may be censored because of intercurrent death of the host animals, limitations of the follow-up period, or the number of cured tumors. Under the general assumptions of log-normally distributed data and independence of the censoring event and the therapy effect, it is shown using computer simulations that the estimate of the median growth delay according to the product limit method of Kaplan and Meier, which allows inclusion of censored data, is unbiased. Omission of censored growth delay times from incomplete accrued data often leads to biased estimates. The power of statistical tests for qualitative comparison of two therapy groups with incomplete sets of data from growth assays was also studied. In the absence of censoring, the power of the different tests is about the same. At higher censoring rates of 40%, however, tests applicable to censored data (log-rank test, Gehan-Wilcoxon test) have a markedly higher power than tests applied to the reduced set of complete observed growth delays (mu test, t test). Although complete observation of tumor regrowth should be strived for, growth delay experiments with very delicate animal tumor models can easily result in censored data. The methods presented permit quantitative and qualitative analysis of growth delay data up to a censoring rate of over 30%, if growth delays and censoring events are independent.
亚根治性治疗后实验性肿瘤的生长延迟时间可能因宿主动物的并发死亡、随访期的限制或治愈肿瘤的数量而被截尾。在数据呈对数正态分布以及截尾事件与治疗效果相互独立的一般假设下，通过计算机模拟表明，根据允许纳入截尾数据的Kaplan-Meier乘积限方法对中位生长延迟的估计是无偏的。从不完整的累积数据中省略截尾的生长延迟时间通常会导致有偏估计。还研究了对来自生长试验的两组不完整数据进行定性比较的统计检验功效。在没有截尾的情况下，不同检验的功效大致相同。然而，在截尾率较高（40%）时，适用于截尾数据的检验（对数秩检验、Gehan-Wilcoxon检验）比应用于减少的完整观察到的生长延迟数据集的检验（μ检验、t检验）具有明显更高的功效。尽管应努力实现对肿瘤再生长的完整观察，但对于非常精细的动物肿瘤模型进行生长延迟实验很容易产生截尾数据。如果生长延迟和截尾事件相互独立，所提出的方法允许对高达30%以上截尾率的生长延迟数据进行定量和定性分析。
