According to the American Cancer Society, there are 5 main categories of chemotherapy drugs that are used to fight cancer. They are:
1. Alkylating agents-that work directly on the cancer cell's DNA to prevent it from replicating. Busulfan, Cyclophoshamide and Melphalan are examples of Alkylating agents.

2. Nitrosureas-that inhibit a cancer cell's enzymes needed for DNA repair. Carmustine and Lomustine are examples of Nitrosureas.

3. Antimetabolites-that interfere with both a cancer cell's DNA and RNA. 5-Fluorouracil, Methotrexate and Fludarabine are examples of Antimetabolites.

4. Antitumor Antibiotics-that also interfere with a cancer cell's DNA in addition to changing its cellular membrane-the outside layer of protective coating. Bleomycin, Doxorubicin and Idarubicin are examples of Antitumor Antibiotics; and,

5. And Mitotic Inhibitors-which are plant alkaloids that inhibit enzymes needed for protein synthesis in the cancer cell. Docetaxel, Etoposide and Vinorelbine are examples of Mitotic Inhibitors.