Chemotherapy is the use of drugs to kill cancer cells and reduce risk of cancer recurrence. There are more than 200 chemotherapy drugs, according to www.chemocare.com. Chemotherapy treatments are often classified according to how they kill cancer cells and their chemical structure. The most common types of chemotherapy drugs include alkylating agents, antimicrotubule agents and antimetabolites. In some cases, different types of chemotherapy drugs are combined to enhance their effectiveness. Most chemotherapeutic treatments kill both cancerous and normal cells.
Alkylating agents
Alkylating agents are chemicals which bind to DNAs in the cells. The therapeutic effect of alkylating agents results from their ability to interfere with rapidly proliferating tissues. In the past 90 years, alkylating agents have played an important role in the treatment of a wide range of cancers including leukemias, lymphomas and solid tumors.
Alkylating agents also cause moderate toxicity to a number of organs, including the bone marrow and the intestinal mucosa. The level of toxicity depends on the type of drug, dosage and duration of exposure. The most well-known clinically useful alkylating agents include carboplatin for ovarian cancer; cisplatin for breast cancer, testicular cancer, head and neck cancer; streptozotocin for pancreatic tumors; and temozolomide for brain tumors.
How aklylating agents are administered varies from capsule form to infusion into a vein.
Antimetabolites
Antimetabolites prevent normal development and division of cells by interfering with normal growth of DNA and RNA in the cells. RNA is central to synthesis of proteins in the cells.
One of the most well-known antimetabolites is 5-FUfluoropyrimidine 5-fluorouracil (5-FU). It is one of the most widely used chemotherapy agents and is used to treat solid tumors, including colon, rectal, gastric, pancreatic, anal, breast, head-and-neck and ovarian cancers. 5-FU attacks cancer cells in various ways, including interfering with DNA repair and synthesis, interfering with RNA processing and activation of programmed cell-death pathways.
5-FU can be administered as a topical ointment or injection to a vein.
Antimicrotubule Agents
Microtubules are a key component of the cytoskeleton, a dynamic structure that is responsible for cell shape and cellular movements. Microtubles also serve as the backbone of the transport system for nutrients within the cells. One of the hallmarks of microtubules is their ability to continuously grow, then disassemble. This enables cells to change their shape and move inside the tissues.
Antimicrotubule agents, such as paclitaxel and docetaxel, bind to tubulin-binding sites and stabilize microtubles, which eventually leads to mitotic arrest and cell deaths.
The most well-known antimicrotubule agents are paclitaxel for breast, ovarian and gastric cancer; vincristine for testicular cancer, lymphoma, acute leukemia, neuroblastoma and multiple myeloma; and docetaxel for breast, prostate and gastric cancers.
Antimicrotubule agents, such as paclitaxel, vincristine, docetaxel, are usually given as an injection or infusion into the vein.
