It was reasoned that an agent that damaged the rapidly growing white blood cells might have a similar effect on cancer. Therefore, in the 1940's several patients with advanced lymphomas were given the drug (by vein, rather than by breathing the irritating gas). Their improvement, although temporary, was remarkable. That experience provided the impetus for the study of other substances that might have similar effects against cancer - as a result, many additional drugs have been developed to treat many other types of cancer.
|Chemotherapy is sometimes the first choice for treating
many cancers. It differs from surgery or radiation in that it is almost always used as a systemic
treatment. This means the drugs travel throughout the whole body or system rather than
being localized to one area such as the breast, lung, or colon. This is important because
chemotherapy can reach cancer cells that may have spread to other parts of the body.
There are now well over 90 drugs used for chemotherapy and many more are expected to become available soon. These chemotherapy drugs vary widely in their chemical composition, how they are taken, their usefulness in treating specific forms of cancer, and their side effects. The NCCN has specific drug protocols that can be accessed on line (here) a typical chemotherapy protocol for combining drugs to treat breast cancer is here.
The increasing understanding of genetics and cancer is opening up new areas of attack at creating effective cancer drugs (go here and here for a nice discussion of targeted therapies). Targeted therapy is a type of medication that blocks the growth of cancer cells by interfering with specific targeted molecules needed for carcinogenesis and tumor growth,rather than by simply interfering with rapidly dividing cells (eg. with traditional chemotherapy). Targeted cancer therapies may be more effective than current treatments and less harmful to normal cells. The main categories of targeted therapy are small molecules: Imatinib mesylate (Gleevec), Gefitinib (Iressa), Erlotinib (Tarceva) Bortezomib (Velcade) and monoclonal antibodies: (Rituximab, Trastuzumab (Herceptin), Cetuximab (Erbitux), Bevacizumab (Avastin) go here.