Carcinogenesis

Carcinogenesis
• The term cancer describes a subset of neoplastic lesions.
• A neoplasm is an abnormal mass of tissue that results when cells divide more than they should or do not die when they should.
• Neoplasms may be either benign or malignant (tumor).
• Metastases are secondary growths of cells from the primary neoplasm.
• A carcinogen is any substance that has the potential to cause cancer in living tissues.

Numerous chemicals and many other factors can alter the structure of the genome and/or the expression of genetic information, with the subsequent appearance of cancer. However, cancer as a disease usually develops slowly, with a long latent period between the first exposure to the chemical carcinogen and the ultimate development of malignant neoplasia, in which various biological structural and functional alterations are involved.

The Pathogenesis of Neoplasia:
The pathogenesis of neoplasia consists of three operationally defined stages, beginning with initiation, followed by an intermediate stage of promotion, from which evolves the stage of progression.