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Incorporating additional biological phenomena into two-stage cancer models
R L Sielken1, R S Bretzlaff, D E Stevenson
1Sielken, Inc., Bryan, Texas 77802.
Progress in Clinical and Biological Research
|January 1, 1994
Summary
This study addresses challenges in cancer potency assessment, particularly the influence of animal background rates. It introduces improved quantitative methods and software for more biologically relevant dose-response modeling.
Area of Science:
- Toxicology
- Carcinogenesis Research
- Quantitative Risk Assessment
Background:
- The Armitage-Doll multistage carcinogenesis model faces implementation challenges.
- Animal background transition rates significantly impact human cancer potency estimations.
- Current methods for cancer potency assessment require refinement for greater biological relevance.
Purpose of the Study:
- To offer risk assessors improved alternatives for quantitative cancer potency assessment.
- To introduce computer software facilitating the use of various dose-response models.
- To enhance the biological relevance of dose scales beyond administered dose.
Main Methods:
- Discussed difficulties in implementing Armitage-Doll-type models.
- Developed computer software for multistage, tolerance, and multihit dose-response models.
- Incorporated biologically relevant dose scales (delivered, biologically effective) and interindividual variability.
Main Results:
- Identified influence of animal background transition rates on cancer potency bounds.
- Facilitated use of diverse dose-response models, including extensions with cell proliferation.
- Enabled consideration of interindividual variability in dose and response probability.
Conclusions:
- The developed software and methods offer improved quantitative cancer potency assessment.
- Biologically relevant dose scales and interindividual variability enhance risk assessment accuracy.
- The MVK two-stage model provides potential for better low-dose behavior estimates by incorporating cell proliferation.