Modelling the Relative and Absolute Risks of Radiation-Induced Cancers
[Read before the Royal Statistical Society at a meeting organized by the Medical Section on Wednesday, January 14th 1987, the President Professor J. Durbin in the Chair] SUMMARY Simple models for the increased numbers of cancers that will occur as a result of exposure to ionizing radiation are useful in formulating policy on xadiological protection. In this paper consideration is given to whether it is more appropriate to base such models on a proportional hazards (relative risk) or an additive hazards (absolute risk) model. The choice is important as there is a large amount of variation in the baseline hazard rate with age. A parametric family of models is proposed, that includes both proportional and additive hazards models as special cases. Examples are given in which the wider family of models is fitted to data from cohort studies of patients with ankylosing spondylitis given x-ray therapy and atomic bomb survivors. Diagnostic procedures relating to the choice of model are considered. Some implications of the findings are discussed.