Topic overview

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Chemical carcinogenesis is organized around initiation, an irreversible DNA alteration, and promotion, which stimulates proliferation without directly causing DNA damage. The topic surveys chemical agents and associated cancers, including aflatoxin, aromatic amines, asbestos, and vinyl chloride. It then considers oncogenic viruses: examples include HPV proteins that disrupt p53 and Rb, and viral mechanisms linked to lymphoma, liver cancer, and other malignancies. Physical carcinogenesis covers UV-induced pyrimidine dimers and ionizing-radiation damage such as DNA breaks and reactive oxygen species. Together, these mechanisms show how distinct exposures can drive cancer through genetic injury, altered growth signaling, or chronic inflammatory effects.