Radiation carcinogenesis: cumulative empirical distribution functions and risk projection models

The use of cumulative empirical distribution functions (CEDF) in connection with the prediction of radio-induced cancer risk is discussed. Two models are generally used for risk prediction: the relative risk and the absolute risk models. It can be easily demonstrated that if the relative projection model is valid, then the CEDFs of the cohort exposed to radiation and of the non-exposed cohort are the same. Land and Tokunaga have shown that for several sets of data the CEDF of exposed and non-exposed cohorts are indistinguishable. They used this result to recommend the use of the relative risk projection model and the rejection of the absolute projection model. This report discusses their argument and shows that when the absolute projection model is valid, the non-exposed and exposed CEDFs are also indistinguishable.