Moger Tron A, Aalen Odd O, Halvorsen Tarje O, Storm Hans H, Tretli Steinar
Section of Medical Statistics, University of Oslo, P.O. Box 1122 Blindern, N-0317 Oslo, Norway.
Biostatistics. 2004 Jan;5(1):1-14. doi: 10.1093/biostatistics/5.1.1.
The incidence of testicular cancer is highest among young men, and then decreases sharply with age. This points towards a frailty effect, where some men have a much greater risk of testicular cancer than the majority of the male population. Those with the highest risk get cancer, drain the group of individuals at risk, and leave a healthy male population which has approximately zero risk of testicular cancer. This leads to the observed decrease in incidence. We discuss a frailty model, where the frailty is compound-Poisson-distributed. This allows for a non-susceptible group (of zero frailty). The model is successfully applied to incidence data from the Danish and Norwegian registries. It is indicated that there was a decrease in incidence for males born during World War II in both countries. Bootstrap analysis is used to find the degree of variation in the estimates. In the Armitage-Doll multistage model, the estimated number of transitions needed for a cell to become malignant is close to 3 for non-seminomas and 4 for seminomas in both the Danish and Norwegian data. This paper demonstrates that a model including a frailty effect fits the incidence data well and gives interesting results and interpretations, although this is no proof of the effect's truth.
睾丸癌的发病率在年轻男性中最高，然后随着年龄的增长急剧下降。这表明存在一种脆弱性效应，即一些男性患睾丸癌的风险比大多数男性人群要高得多。那些风险最高的人患了癌症，耗尽了有风险的人群，留下了患睾丸癌风险几乎为零的健康男性群体。这就导致了观察到的发病率下降。我们讨论了一种脆弱性模型，其中脆弱性服从复合泊松分布。这允许存在一个非易感群体（脆弱性为零）。该模型成功应用于丹麦和挪威登记处的发病率数据。结果表明，在这两个国家，二战期间出生的男性发病率都有所下降。使用自助法分析来确定估计值的变化程度。在阿米蒂奇 - 多尔多阶段模型中，对于丹麦和挪威的数据，非精原细胞瘤细胞变为恶性所需的估计转变次数接近3次，精原细胞瘤接近4次。本文表明，包含脆弱性效应的模型能很好地拟合发病率数据，并给出了有趣的结果和解释，尽管这并不能证明该效应的真实性。
