Chemotherapy drugs destroy cancer cells, which normally grow more rapidly than normal cells. Chemotherapy agents work in different ways and can be grouped in different categories, depending on their chemical structures and mode of action, although some drugs may overlap several categories. Some drugs used to destroy cancer cells attack cells in other ways and technically don't classify as chemotherapy, although they're used to treat cancer, the American Cancer Society explains. Most drugs within a certain class have similar side effects and actions.
Alkylating Drugs
Alkylating drugs form a chemical bond with DNA, which damages the DNA and prevents cell replication, keeping cancer from growing and spreading. Alkylating drugs cause hair loss, disturb the stomach lining and suppress bone marrow and the immune system. Leukemia can follow the use of alkylating drugs, usually occurring five to 10 years after chemotherapy, the Merck Manual states. Typical alkylating drugs include nitrogen mustards such as cyclophosphamide and chlorambucil, nitrosoureas and alkyl sulfonates.
Platinum drugs such as cisplatin are often grouped with alkylating drugs because they work similarly. Platinum drug side effects include those of other alkylating drug, but also include nerve and kidney damage and hearing loss, the Merck Manual reports. Alkylating drugs are used to treat many cancers, including leukemia, lymphoma and Hodgkin's disease.
Anti-Tumor Drugs
Anti-tumor drugs block enzymes and change the need for DNA to replicate. Doxorubicin and other anti-tumor drugs belonging to a class called anthracyclines can cause heart problems, the American Cancer Society warns. Lifetime dose limits may be placed on the use of these drugs. Anti-tumor drugs treat prostate cancer, breast cancer and leukemia, among others.
Anti-Metabolite Antibiotics
Anti-metabolite antibiotics block enzymes necessary for RNA and DNA replication. Methotrexate, 5-FU and Ara-C are typical anti-metabolites. Anti-metabolites and alkylating drugs have similar side effects, but anti-metabolites don't increase the risk of developing leukemia. Anti-metabolites treat breast, ovarian and intestinal cancer, plus leukemias, the American Cancer Society reports.
Mitotic Inhibitors
Mitotic inhibitors, also called anti-mitotics, slow cancer-cell division. This category of drugs, which includes vincristine, paclitaxol and vinorelbine, causes symptoms similar to alkylating drugs, except for the increased leukemia risk. Drugs in this class can cause nerve damage. Mitotic inhibitors treat breast and lung cancers, lymphomas and leukemias.
Topoisomerase Inhibitors
Topoisomerase inhibitors interfere with a cancer cell's ability to duplicate DNA strands. These drugs increase the risk of developing acute myelogenous leukemia two to three years after chemotherapy. Mitoxantrone, a drug classified as an anti-tumor drug, as well as a topoisomerase inhibitor, can also cause heart damage. These medications treat some leukemias, as well as lung, ovarian and gastrointestinal cancers, among others.
