Age-adjustment in experimental animal data and its application to lung cancer in radon-exposed rats

Radiation and Environmental Biophysics
W F HeidenreichG Monchaux

Abstract

Procedures for age-adjustment of cancer fractions are proposed which do not require fixed age intervals. The full available information on survival times can then be used, which is especially important in small treatment groups. For incidental cancers a non-decreasing prevalence function and for fatal cancers the Kaplan-Meier estimator is used. In the latter case, the estimated competing risk of the control population is standardized, not its true survival. This makes the technique also applicable to treatment groups with high incidence, which otherwise may give adjusted rates above 100%. In the application part these age-adjustment techniques are used here to study lung cancer in radon-exposed Wistar and Sprague-Dawley rats. The data include a classification in fatal and incidental lung cancers. For fatal lung cancer, the lifetime excess absolute risk (LEAR) at 1 WLM averaged over all exposed groups is 0.67x10(-4) for the Wistar rats, while for the Sprague-Dawley rats it is 0.40x10(-4). For the Sprague-Dawley rats, there are several groups exposed later in life. When the averaging is restricted to animals with start of exposure prior to 150 days of age, the weighted average risk among the Sprague-Dawley rats is 0.79x10(-4). Co...Continue Reading

References

Dec 21, 2002·Radiation Research·Vincenzo Di MajoVincenzo Covelli

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Citations

May 3, 2005·Radiation and Environmental Biophysics·W F HeidenreichM Rosemann
Sep 28, 2005·Radiation and Environmental Biophysics·W F HeidenreichG Monchaux
Apr 3, 2012·Radiation and Environmental Biophysics·W F Heidenreich, M Rosemann
Dec 22, 2005·International Journal of Radiation Biology·C G CollierR Haylock
Apr 9, 2013·Radiation Research·W F HeidenreichS Pazzaglia

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