DESIGN AND ANALYSIS OF EPIDEMIOLOGIC STUDIES OF EXCESS CANCER AMONG CHILDREN EXPOSED TO CHERNOBYL RADIONUCLIDES

Within the last decade, a substantial amount of attention has been dev oted to etiological research on the association between exposure to fa llout radionuclides from the Chernobyl accident and radiation-induced late effects (cancer) among children. A majority of the studies comple ted to date have been of the descriptive type, which only correlate av erage population exposure with average rate of cancer incidence as a f unction of calendar period. Since individual dosimetry is not performe d in descriptive studies, it is unclear whether exposure precedes the development of cancer and a final decision cannot be made regarding th e association between radiation exposure and cancer. This paper review s the background epidemiology and outlines an analytical study design that is needed to clarify the unclear association between Chernobyl fa llout exposure and childhood cancer. We discuss the essential elements of an analytical case-control design such as genetic predisposition, vital statistics, sample size and power determinations, ascertainment of cases and controls, and phenomenological dose modeling to establish individual doses. Examples such as cytogenetic biodosimetry, medical radiation dosimetry, and cytogenetic characterization of leukemia to m inimize exposure and diagnostic misclassification are provided. We rec ommend the analytical methods described in this paper for studying the role of Chernobyl radionuclides and development of childhood cancer.