[Dentification and correction of the lead-time bias and length bias in cancer screening studies].

ABSTRACT

Lead-time bias and length bias were common systematic errors in observational screening studies, which might be a common cause of overstating or distorting the true screening effects. One of key concerns in observational screening studies was how to estimate the screening effects based on the consideration of these two biases. This paper illustrated how to identify and correct the lead-time bias using the tumor volume doubling time and the non-homogeneous Poisson process, and how to correct the length bias using a weighted method. The application conditions of each method were also discussed to present several useful toolboxes to correct the lead-time bias and length bias appropriately and evaluate the effectiveness of the cancer screening program accurately.