Chapter 078. Prevention and Early Detection of Cancer (Part 3)

Cancer Chemoprevention Chemoprevention involves the use of specific natural or synthetic chemical agents to reverse, suppress, or prevent carcinogenesis before the development of invasive malignancy.Cancer develops through an accumulation of genetic and epigenetic changes that are potential points of intervention to prevent cancer. The initial changes are termed initiation. The alteration can be inherited or acquired through the action of physical, infectious, or chemical carcinogens. Like most human diseases, cancer arises from an interaction between genetics and environmental exposures (Table 78-1). Influences that cause the initiated cell to progress through the carcinogenic process and change phenotypically are termed promoters....
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Chapter 078. Prevention and Early Detection of Cancer (Part 3) Chapter 078. Prevention and Early Detection of Cancer (Part 3) Cancer Chemoprevention Chemoprevention involves the use of specific natural or synthetic chemicalagents to reverse, suppress, or prevent carcinogenesis before the development ofinvasive malignancy. Cancer develops through an accumulation of genetic and epigeneticchanges that are potential points of intervention to prevent cancer. The initialchanges are termed initiation. The alteration can be inherited or acquired throughthe action of physical, infectious, or chemical carcinogens. Like most humandiseases, cancer arises from an interaction between genetics and environmentalexposures (Table 78-1). Influences that cause the initiated cell to progress throughthe carcinogenic process and change phenotypically are termed promoters.Promoters include hormones such as androgens, linked to prostate cancer, andestrogen, linked to breast and endometrial cancer. The distinction between aninitiator and promoter is sometimes arbitrary; some components of cigarettesmoke are complete carcinogens, acting as both initiators and promoters. Cancercan be prevented or controlled through interference with the factors that causecancer initiation, promotion, or progression. Compounds of interest inchemoprevention often have antimutagenic, antioxidant, anti-inflammatory,antiproliferative, or pro-apoptotic activity (or a combination). Table 78-1 Suspected Carcinogens Carcinogensa Associated Cancer or Neoplasm Alkylating agents Acute myeloid leukemia, bladder cancer Androgens Prostate cancer Aromatic amines (dyes) Bladder cancerArsenic Cancer of the lung, skinAsbestos Cancer of the lung, pleura, peritoneumBenzene Acute myelocytic leukemiaChromium Lung cancerDiethylstilbestrol (prenatal) Vaginal cancer (clear cell)Epstein-Barr virus Burkitts lymphoma, nasal T cell lymphomaEstrogens Cancer of the endometrium, liver, breastEthyl alcohol Cancer of the liver, esophagus, head and neck Helicobacter pylori Gastric cancer, gastric MALT lymphoma Hepatitis B or C virus Liver cancer Human immunodeficiency virus Non-Hodgkins lymphoma, Kaposis sarcoma, squamous cell carcinomas (especially of the urogenital tract) Human papilloma virus Cervix cancer, head and neck cancer Human T cell lymphotropic Adult T cell leukemia/lymphomavirus type I (HTLV-I) Immunosuppressive agents Non-Hodgkins lymphoma(azathioprine, cyclosporine,glucocorticoids)Nitrogen mustard gas Cancer of the lung, head and neck, nasal sinusesNickel dust Cancer of the lung, nasal sinusesPhenacetin Cancer of the renal pelvis and bladderPolycyclic hydrocarbons Cancer of the lung, skin (especially squamous cell carcinoma of scrotal skin)Schistosomiasis Bladder cancer (squamous cell)Sunlight (ultraviolet) Skin cancer (squamous cell and melanoma)Tobacco (including smokeless) Cancer of the upper aerodigestive tract, bladderVinyl chloride Liver cancer (angiosarcoma)a Agents that are thought to act as cancer initiators and/or promoters.