Online Program

At What Age Should Cancer Screening Be Started? (304124)

Keywords: sensitivity, sojourn time, transition density, over diagnosis, lead time.

A method using probability of incidence was developed to decide when to initiate cancer screening. The probability of incidence is a function of screening sensitivity, the time duration in disease-free state and sojourn time in preclinical state; and it is monotonically increasing with a person’s age. So we can find a unique solution of the first screening age by limiting this probability to a small value, such as 5% or 10%. That is, with 95% or 90% probability one will not be a clinical incident case before the first exam. Once 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 the male and female heavy smoker cohorts in the National Lung Screening Trial using low dose computerized tomography (NLST-CT). The method is applicable to other kinds of cancer screening. And the predictive information can be used by policy makers to make decisions on when to initial cancer screening.