Date on Master's Thesis/Doctoral Dissertation


Document Type

Master's Thesis

Degree Name


Department (Legacy)

Department of Biostatistics

Committee Chair

Wu, Dongfeng

Author's Keywords

Cancer screening; Cancer; Lead time; Breast cancer; Simluation; Colon cancer


Medical screening; Cancer--Diagnosis


PURPOSE: The purpose of this paper is to examine the lead time distribution in cancer screening trials when lifetime is a random variable in order to determine optimal initial age at screening and screening frequency. METHODS: Simulation was used in order to estimate the distribution of the lead time for a hypothetical individual with a future screening schedule. The lifetime distribution used comes from the Social Security Administration's actuarial life tables. The lead time distribution was then calculated based on two different sojourn time distributions (log-logistic and exponential) with four mean sojourn times (2, 5, 10, and 20 years), using three different initial screening ages, to=40, 50, 60, and four different screening frequencies, every six months, every year, every 1.5 years, and every two years for both males and females. RESULTS: Smaller time intervals between screenings yield a smaller probability of no benefit and a greater expected lead time.