Abstract
Cancer is a consequence of malfunction of the replicative cell cycle caused by acquisition of independence from proliferative and restrictive controls in the process. Such alteration may be driven by unrepaired mutations in proto-oncogenes and anti-oncogenes or by genetic insults of environmental, infectious, or spontaneous origin. The consequence of mutations may be reflected at any of a number of locations in the transductive pathways from receptor to nucleus which upset normal homeostatic balance between the opposing forces for promotion or restraint of cell proliferation. About 15% of human cancers are caused primarily by viruses that bring about aberrations in gene structure and function or that express proteins that bind to cell regulatory proteins. The means for achieving immunoprophylaxis of viral cancers, such as hepatitis B or Marek's disease, are based on prior specific perturbation of the immune system, causing it to respond rapidly and effectively in preventing infection on subsequent contact with the corresponding agent. Existing cancers of viral origin and those of nonviral causation come together in attempted immunotherapy. Cure is far more difficult to achieve than prevention and relies on the principle that tumor cells can display abnormal markers on the cell surface that are capable of being detected and engaged by an effective immune response. Efforts to prevent and cure cancer of viral, spontaneous, or environmental origin are a worthy pursuit and must take account of the most advanced information relating to the chemistry of the cell cycle and to the function of the immune system.
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