Chemicals Used in Chemotherapy
Chemotherapy is used in patients to stop the growth and spread of cancer at all of its stages of development. What is little known is exactly what drugs are used in chemotherapy and why. Learning about the categories of drugs and their purpose can help patients make an informed decision about cancer treatment options.
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Types
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There are more than 300 drugs that are used in chemotherapy, but they all generally fall into one of four categories, depending on their intended purpose: antimetabolites, alkylating agents, topoisomerase inhibitors and anthracyclines. The combination of these drugs attacks the ability of cancer cells to survive, reproduce and propagate or metastasize. During chemotherapy, some cancers may be resistant to one or more drugs, meaning the regimen may be changed, leading to a profusion of chemicals.
Antimetabolites
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Cancer cells are still living and as such need to metabolize food to continue to live and grow. Antimetabolites interfere with a cancer cell's ability to metabolize food into energy. Chemicals such as 6-mercaptopurine and 5-Azacitidine are drugs that are administered subcutaneously (under the skin) or intravenously (directly into the veins), though some may be administered orally.
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Alkylating agents
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Alkylating agents damage the cancer cell's deoxyribonucleic acid, or DNA, preventing them from reproducing and spreading. This prevents tumor growth as well, though not all cancers manifest as tumors. Cyclophosphamide, abraxane and mechlorethamine hydrochloride are examples of alkylating agents used in chemotherapy. These are usually given intravenously.
Topoisomerase inhibitors
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Topoisomerase inhibitors break down the DNA structure of the cancer cell and inhibit a single helix strand from bonding to another, thus preventing reproduction. In this manner, it acts similar to alkylating agents but attacks the DNA much earlier in the life cycle of the cancer cell--during actual reproduction--whereas alkylating agents attack cells after reproduction. Some common topoisomerase inhibitors are CPT-11, Camptothecan and Taxol. Most of these drugs are administered intravenously.
Anthracyclines
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Anthracyclines cause "free radical" radiation damage to cells by stripping away some of the protection that cancer cells have, damaging the ribose of the DNA, disrupting the reproduction of the cell. Common anthracyclines include Mitoxantrone, Doxorubicin and Daunorubicin. These drugs are also administered intravenously, mostly because outside of the bloodstream, they may cause tissue damage and blistering.
Others
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There are also other drugs that may be involved in chemotheraphy, including hormone inhibitors, cortosteroids and drugs to control the side effects of some chemotherapy drugs. This adds to the amount of chemicals introduced into the body during chemotherapy, which may add to some of the confusion over the purpose and effects of these medications. Close consultation with an oncologist as well as cancer support and information groups is highly recommended for potential and current chemotherapy patients.
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