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CHAPTER 20 Cancer 20-1 Benign and Malignant Tumors Abnormal cell division may lead to benign tumors, which stop growing, or malignant tumors, which can invade other parts of the body. Cancer cells often migrate to other sites. 20-2 How Cancer Forms The conversion of a normal cell to a cancerous one involves two steps. Mutations in two groups of genes are primarily responsible for cancer. Several physical and biological agents are also responsible for producing cancer. Some carcinogens exert their effect outside of the DNA. Cancers develop many years after the initial exposure to a carcinogen. 20-3 Cancer Treatments Tumors can be removed surgically or treated with chemotherapy and radiation. Stimulating the body to produce antibodies and T cells that attack tumors can help eliminate tumors. Liposomes containing cancer-killing chemicals or monoclonal antibodies attached to chemotherapeutic agents can deliver a lethal dose of these chemicals directly to cancers. Reduced blood vessel development in tumors successfully stops cancers from growing. Blocking genes involved in cell replication or altering their products could help doctors kill cancer cells. Drugs combined with light therapy may prove to be an effective treatment in some forms of cancer. The earlier a cancer is detected and treated, the better one’s chances of survival. Preventing cancer may be the best approach of any. © 2012 Jones and Bartlett Learning, LLC