The anticancer drugs usually follow the antimicrobials in most pharmacology textbooks. This is because the drugs, in many cases, are similar.
Many students get really bogged down with the anticancer drugs. There are an awful lot of drugs with known mechanisms of action and multiple side effects that can be quite serious. However, there are some general principles of the use of these drugs that can be emphasized. In fact, these principles are more important than the individual agents. So, for the purposes of this book, focus on name recognition (be sure that you recognize a particular agent as an anticancer drug) and a few specific toxicities. Do not try to remember every type of cancer that the drug is used for. You can add some of this information later as you use these drugs in the clinical setting. Get a handle on the overall picture before you focus on the details.
Many anticancer drugs have had several names over the years. Do not let this confuse you.
This is another very annoying thing about this group of drugs. Some of these agents are known by several names.
Cytotoxic drugs—drugs which block cell replication
Alkylating agents, including nitrogen mustards and nitrosoureas
Antimetabolites, including folate antagonists, purine and pyrimidine analogues
Antibiotics and other natural products, including anthracyclines and vinca alkaloids
Antibodies—to improve specificity
Other cytotoxic drugs
Hormonal agents—drugs for hormone-sensitive tumors
Signal Transduction Inhibitors
The drugs can be divided into three simple groups: the cytotoxic drugs, the hormones, and the signal transduction inhibitors. All of the alkylating agents, antibiotics, antimetabolites, and miscellaneous drugs are cytotoxic drugs—they kill cells, particularly dividing cells. Therefore, all of the following terminology and general principles apply to the cytotoxic drugs. The hormonal agents are used for tumors of the hormonally sensitive tissues, such as breast and prostate. As always there are some drugs that do not fit neatly into these two categories.
TERMINOLOGY AND GENERAL PRINCIPLES OF THERAPY
Anticancer therapy is aimed at killing dividing cells. There are normal host cells that are also dividing. Effects on these cells cause side effects.
This is a bit simplistic but serves our purposes for now. In antimicrobial therapy, the object is to kill the invading bacteria without harming the host. In anticancer therapy, the object is to kill the cancer cells without harming the normal cells. This is difficult because the cancer cells are also human (or host) cells. The cancer cells are basically human cells that have lost control of cell division. Therefore, anticancer treatment is, in large part, aimed at killing dividing cells. Remember that cells in certain places in the body—the epithelium of the gastrointestinal (GI) tract, hair follicles, and bone marrow, especially—are dividing continuously. Effects on these dividing cells cause adverse effects.