This text includes a comprehensive updated analysis of cancer risk assessment procedures, with particular attention to biologically-based modelling. The presented arguments include the basic assumptions of cancer risk assessment methods, their biological basis and theoretical background, the relevant data sources, the multistage models (including the two-stage and clonal expansion models and pharmacokinetic models), and the relevant biomarkers, together with fundamental statistical considerations and selected case studies and examples of practical applications. The uncertainty of assessment and the practical use of the proposed methods are suggested. The book examines in detail the updated biologically-based carcinogenic risk assessment procedures together with the usually employed procedures, as well as background information on which they are based. It also proposes new ideas and methods in this field. Furthermore, it includes criteria and methods for practical application and use of the examined procedures.