Cytotoxic refers to a substance or process which results in cell damage or cell death. The prefix “cyto” refers to cell and “toxic” to poison.
Cytotoxic Chemotherapy Drugs
Most of the time the term “cytotoxic” refers to the effect that a chemotherapy drug has on cancer cells. In this sense, a cytotoxic agent may be differentiated from one that is cytostatic. A cytostatic medication would, in contrast, inhibit cell division and growth but would not result in cell death directly.Cytotoxic drugs work by interrupting cells at particular places in the growth cycle. Cytotoxic drugs are most likely to affect cells that are growing rapidly, for example, cancer cells, hair follicles, bone marrow and cells lining the stomach and intestines. The reason that most chemotherapy uses a combination of drugs and that most chemotherapy cycles are repeated is because cells are in various places in the division process.
There are other cytotoxic substances used for a wide array of functions. As with cytotoxic chemotherapy drugs, this simply means that they kill cells.
Cytotoxic T cells
Cytotoxic agents are not just created to destroy cancers and control diseases. Our bodies also manufacture cytotoxic T-cells (cytotoxic T lymphocytes). Cytotoxic T cells are part of the immune system, which searches for, finds and destroys cells infected by viruses as well as cancer cells.One of the most rapidly advancing areas of cancer research is now focusing on harnessing and stimulating our own cytotoxic cells to fight cancer in our bodies.
Humans are not alone in their use of cytotoxic T cells. Some venoms, such as those emitted by vipers, cobras and violin spiders, are also cytotoxic.
Mechanism of Action
Cytotoxic agents can kill cells in several ways. They may harm the cell so that its cell membrane is weakened and the cell explodes (lysis,) or they may interfere with cell division so the cell stops growing and dividing.
Dangers of Cytotoxic Drugs and Agents
Cytotoxic drugs can kill cancer cells but they can also damage normal, healthy cells.
Cytotoxic vs Genotoxic
There is much confusion between the terms cytotoxic and genotoxic. The term cytotoxic refers to the ability of a substance to cause damage to cells. The term genotoxic refers to the ability of a substance to directly damage DNA in cells.
A few other definitions are important to explain when talking about cytotoxicity. These include:
- Carcinogenic – Exposure to a cytotoxic substance has the ability to cause DNA damage that could ultimately lead to the development of cancer.
- Mutagenic – Exposure to cytotoxic substances could potentially instead damage the chromosomes in a fetus.
This is why it is extremely important for people to practice caution when they are handling cytotoxic drugs and substances.
For those who work with cytotoxic medications or other substances, precautions are recommended specifically to avoid carcinogenicity and mutagenicity. The specific precautions will vary considerably based on the route of possible exposure but may include:
- Gloves, with cuffs tucked under the gloves
- Long sleeve clothing
- Disposable gowns
- Safety glasses
- Respiratory protection