Chemotherapy drugs are used to treat and stop the spread of a variety of cancers and leukemias. They work by killing the cancer cells or by stopping them from dividing and reproducing. Chemotherapy drugs can be administered intravenously (IV), orally, under the skin (subcutaneous injection), into the muscle (intramuscular injection), or, rarely, into the fluid around the spine (intrathecal chemotherapy). Patients may receive one or a combination of chemotherapy drugs based on the type of cancer and action of the drugs.
Alkylating Agents
Alkylating agents--the oldest and most commonly used chemotherapy drugs--work in all phases of the cell cycle to damage cell DNA and prevent reproduction. They are used to treat lymphoma, leukemia, multiple myeloma, Hodgkin's disease, sarcoma, and lung, breast and ovarian cancers. Common alkylating agents include nitrogen mustards (chlorambucil, ifosfamide, mechlorethamine, cyclophosphamide and melphalan), nitrosoureas (carmustine, streptozocin and lomustine), triazines (dacarbazine and temozolomide), ethylenimines (altretamine and thiotepa), and the alkyl sulfonate called busulfan.
Antimetabolites
Antimetabolites replace normal RNA and DNA building blocks, causing damage to the cells during the S phase (synthesis phase, when the DNA packaged into chromosomes is replicated) and preventing cell reproduction. Common antimetabolites include capecitabine, gemcitabine, 6-mercaptopurine, 5-fluorouracil, cytarabine, fludarabine, methotrexate and pemetrexed. They can be used to treat breast, ovarian and intestinal cancers, as well as leukemias.
Mitotic Inhibitors and Plant Alkaloids
Mitotic Inhibitors are plant alkaloids and other naturally-derived compounds. They work during the M phase of the cell cycle, which includes the stages of nuclear division (mitosis) and cytoplasmic division (cytokinesis). Examples include estramustine, ixabepilone, taxanes such as docetaxel and paclitaxel, and vinca alkaloids such as vinblastine, vinorelbine and vincristine. They are used to treat breast and lung cancers, leukemias, myelomas and lymphomas, and may increase the risk of peripheral nerve damage.
Topoisomerase Inhibitors
Topoisomerase inhibitors indirectly prevent cells from reproducing by interfering with enzymes called topoisomerases whose job it is to separate DNA strands so they can be copied. Topoisomerase I inhibitors like topotecan and irinotecan and topoisomerase II inhibitors such as etoposide, teniposide and mitoxantrone (also classified as an antitumor antibiotic) are used to treat a variety of leukemias and cancers, including lung, ovarian, and gastrointestinal.
Antitumor Antibiotics
Antitumor antibiotics bind with a cell's DNA and cause it to uncoil, preventing the cell from reproducing. Dactinomycin, bleomycin, and mitomycin are examples of antitumor antibiotic drugs used for chemotherapy. Mitoxantrone is an antitumor antibiotic that is also classified as a topoisomerase II inhibitor.
Anthracyclines are a specific type of antitumor antibiotic that interfere with the enzymes used in DNA replication. Some commonly used anthracyclines are daunorubicin, epirubicin, doxorubicin and idarubicin.
Corticosteroids
Corticosteroids are drugs that mimic the effect of certain hormones in our bodies. Corticosteroids have a number of uses, including reducing nausea and vomiting, reducing the risk of allergic reactions to chemotherapy, and reducing inflammation. When corticosteroids are used to slow the growth of cancer or kill cancer cells, they are considered to be chemotherapy drugs. Examples of corticosteroids include prednisone, methylprednisolone and dexamethasone.
