Chemotherapy treatment uses a variety of different drugs to kill cancer cells or halt their growth. They work by targeting quick-growing cells, which also causes side effects when other, normal fast-growing cells are affected. Some chemotherapy drugs target specific points in the cell cycle, while others are more wide-ranging. Sometimes, the drugs are given singly, while some patients receive a combination of medications. The specific drug choices may depend on the type and degree of cancer, the health of the patient and specific characteristics of a given tumor.
Alkylating Agents
Alkylating agents operate by destroying DNA by inducing breaks in the DNA strand, thereby introducing errors and halting cell reproduction, explains The Merck Manuals Online Medical Library. They include nitrosureas, hydrazines, triazines, ethylenimines, alkyl sulfonates and nitrogen mustards, which are a derivative of mustard gas. They are used in the treatment of breast cancer, leukemia, lymphoma, multiple myeloma, sarcoma, lung cancer and ovarian cancer. Because they directly destroy DNA during any phase of the cell cycle, they damage normal cells, too, especially those in bone marrow. This damage increases the risk of leukemia later in the life of the patient.
Antitumor Antibiotics
Antitumor antibiotics, which include the subgroups anthracyclines and chromomycins, target enzymes used by the cell to assist in DNA replication. Because high doses may lead to heart damage, these drugs often have a lifetime limit on how much of the drug a doctor will prescribe, according to the American Cancer Society.
Antimetabolites
Antimetabolites substitute a nonworking component of DNA or RNA into the replicating genes of a tumor cell, effectively halting the cell's growth, explains Chemocare.com. Breast cancer, ovarian cancer, leukemia and intestinal cancer are typical targets of antimetabolites, although they can be used against many different forms of cancer.
Mitotic Inhibitors
Mitotic inhibitors include plant alkaloids that are derived from natural plant sources. They include vinca alkaloids made from periwinkle and taxanes from Pacific Yew tree bark. These drugs halt mitosis, the M phase of the cell cycle, and can also damage tumor cells that are in other phases, according to the American Cancer Society. Breast cancer, lung cancer, myeloma, lymphoma and leukemia all respond to treatment with mitotic inhibitors. A major side effect is peripheral nerve damage, which increases with larger doses of these chemotherapy drugs, maintains the American Cancer Society.
Toposiomerase Inhibitors
Toposiomerase inhibitors block the action of topoisomerase, an enzyme that is important to cell replication. Some are derived from plant sources, such as the camptothecan analogs, which are made from the plant Camptotheca acuminata, according to Chemocare.com. Common cancers targeted by topoisomerase inhibitors include some leukemias, lung cancer, ovarian cancer and gastrointestinal cancers.
Corticosteroids
Corticosteroids can be used to kill lymphoma, leukemia and multiple myeloma cells and may also be used to ease the side effects of other chemotherapy drugs. In addition to their chemotherapy action, corticosteroids also help reduce nausea, vomiting and allergic reactions caused by cancer treatment, explains the American Cancer Society.
