Excess Lung Cancer Risk Attributable to Low-Dose CT Screening Among Long-Term Smokers

• Activity Number: 145
• Type: Contributed
• Date/Time: Monday, August 5, 2013 : 8:30 AM to 10:20 AM
• Sponsor: Section on Statistics in Epidemiology
• Author(s): Rui Yang*+ and Deborah Goldwasser
• Companies: Quintiles and Rice Univeristy
• Keywords: Two-stage clonal Expansion (TSCE) Model ; Lung Cancer Screening ; Excess Relative Risks ; Radiation-induced Cancers ; Mayo CT Study

Abstract

Objectives: We modify the two-stage clonal expansion (TSCE) model to predict excess relative lung cancer (LC) risk with age-at-exposure when radiation exposure acts to destabilize an existing population of intermediate cells (IC).

Methods: We parameterize the TSCE model to allow the inclusion of a factor r reflecting the enhancing mutagenic effect of radiation exposure on the IC population. We evaluate excess lung cancer risk as a function of baseline lung cancer risk among Mayo CT population. We further examine 10-year excess LC risk by age-at-exposure and absolute LC risk categories for a set of biologically-plausible factors r.

Results: We estimate a destabilization ratio of r=1.008 (p-value 0.0021) associated with a single exposure. Model-based predictions suggest that baseline cumulative LC risk among Mayo CT participants ranging from 0.086 to 0.425 in males and 0.11 to 0.45 in females by age 80. Compared to the lowest baseline risk category, excess relative risk may be up to 5.5 times higher among individuals in the highest category, which indicates that the harms associated with screening are restricted to those may benefit the most from it.