initiation Promotion Cenversion Progression o Defects in Terminal Differentiation Defects in Growth Control Resistance to Cytotoxicity Defects in Programmed Cell Death Clonal Genetic 多因素、多步骤 CELL LESION TUMOA CANCER ETASTASIS s Activation of Proto-Oncogenes Inactivation of Tumor Suppressor Genes Inactivation of Antimetastasis genes Cancer Susceptibility Genes多因素、多步骤