A probability method is developed to decide when to initiate cancer screening for asymptomatic individuals. The probability of incidence is a function of screening sensitivity, time duration in the disease-free state and sojourn time in the preclinical state; and it is monotonically increasing as time increases, given a person’s current age. So a unique solution of the first screening time can be found by limiting this probability to a small value, such as 10% or 20%. That is, with 90% or 80% probability, one will not be a clinical incident case before the first exam. After this age is found, we can further estimate the lead time distribution and probability of over-diagnosis if one would be diagnosed with cancer at the first exam. Simulations were carried out under different scenarios; and the method was applied to two heavy smoker cohorts in the National Lung Screening Trial using low-dose computerized tomography. The method is applicable to other kinds of cancer screening. The predictive information can be used by physicians or individuals at risk to make informed decisions on when to initiate screening.

中文翻译：

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什么时候开始癌症筛查检查？

开发了一种概率方法来决定何时开始对无症状个体进行癌症筛查。发病概率是筛查敏感性、无病状态持续时间和临床前状态停留时间的函数；给定一个人的当前年龄，它随着时间的增加而单调增加。因此，通过将这个概率限制在一个很小的值，例如 10% 或 20%，可以找到第一次筛选时间的唯一解。也就是说，在第一次检查之前，有 90% 或 80% 的概率不会是临床事故病例。找到这个年龄后，如果一个人在第一次检查时被诊断出患有癌症，我们可以进一步估计提前时间分布和过度诊断的概率。在不同的场景下进行了模拟；该方法使用低剂量计算机断层扫描应用于国家肺筛查试验中的两个重度吸烟者队列。该方法适用于其他类型的癌症筛查。医生或有风险的个人可以使用预测信息来就何时开始筛查做出明智的决定。