We've come a long way from those early days of a tiny handful of drugs. Today, "There are about 50 different chemotherapy drugs, that kill cancer cells by attacking their DNA and proteins that are important for cancer cells to grow," explains Dr. Branimir I. Sikic, professor of medicine (oncology) at Stanford University via email.
Here's a list of the main ones:
Alkylating agents: These drugs damage the DNA of cancer cells, hopefully preventing them from reproducing. They are used in the treatment of many cancers because they can be effective throughout the cell cycle.
Antimetabolites: Most commonly used for leukemias, as well as breast, ovarian and intestinal cancers, these drugs shoot to cause damage to the cancerous cells during the phase when they are copying the cell's chromosomes.
Anti-tumor Antibiotics: These attempt to permanently alter cancer cell DNA, so that the cells can't grow or replicate any more.
Topoisomerase inhibitors: Topoisomerase enzymes help separate DNA strands so they can be copied. The inhibitors get in their way to stop that process, and are particularly useful in cancers that affect the lungs, ovaries, GI tract and some leukemias.
Mitotic inhibitors: These are naturally derived compounds, usually from plants. They pack a dual punch by damaging cells throughout their phases, keeping cancer cells from dividing and preventing enzymes from making the proteins necessary for cell reproduction.
The type of chemo regimen a patient is assigned to depends on many factors, like the form of cancer, how far it has spread and so on.
While chemo doses have not changed over the past 50 years or so, there have been other advances to make the medication easier to handle, says Dr. Evelyn Handel, director of the drugs and biologics programs at NCCN in an email interview. "Although the toxicities associated with these medications remain the same, the supportive care medication options we have to treat the toxicities are vastly improved — for example, better antiemetics [drugs that prevent vomiting and nausea], more choices for premedications, antidiarrheals, antihypertensives, etc.," she notes.