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Cancer is a disease characterized by an overgrowth of cells or the disorder of the cell cycle. Cancer cells grow and divide in an unregulated manner, whereas normal, healthy cells do not. Commonly, this unregulated form of cell growth with cancer cells is because of the occurrence of genetic mutations in a cell's DNA. These mutations can be classified as either a gain-of-function or loss-of-function mutation type. Mutations that lead to cancer may be the result of environmental influences, including exposure to carcinogens (cancer-causing agents) and/or mutagens (agents that cause genetic mutations), or they may be inherited. Cancer is treated using both traditional and new therapeutic methods. Traditional methods include surgery, radiation therapy, and chemotherapy (in which chemicals that kill actively-dividing cells are given to the patient). Newer therapies can provide more-targeted treatments. These therapies take advantage of the varying cell surface receptors on the surfaces of cancer cells. Furthermore, immunotherapy can interrupt the cell signaling that leads to cell growth and division, or it can harness the body's own immune system to target and destroy cancer cells.

At A Glance

  • Cancer arises when cells fail to be restrained by the normal devices that stop them from surviving and dividing when conditions are unfavorable.
  • Cancer is caused by gain-of-function mutations in proto-oncogenes or loss-of-function mutations in tumor suppressor genes.
  • Common treatments of cancer include surgery; radiation therapy, in which high doses of radiation are aimed at the tumor to disrupt the DNA; and chemotherapy, in which cytotoxic chemicals are applied in order to kill cancer cells.
  • Because cancer cells carry specific cell surface receptors, tailored therapies offer increased chances of destroying cancer cells.
  • Immunotherapy treatments work either by blocking the binding of signals that bypass normal cell cycle checkpoints or by harnessing the power of the body's own immune system to seek out and destroy cancer cells.