Principles
Chemotherapy, Medline explains, describes treatments that use drugs to poison cancer cells. Many chemotherapy drugs work by causing DNA damage. DNA-damaging drugs affect fast-dividing cancer cells because their DNA is exposed. Other medications work to block some of the cellular processes involved in cell replication. Often chemotherapy drugs are used in combination; the exact combination of drugs used is up to the oncologist and the patient. Different combinations of chemotherapy drugs have distinct side effect profiles and may work better for different kinds of cancer.
Administration
There are many different routes by which chemotherapy can be administered. Some drugs, according to the American Cancer Society, can be given orally, in the form of a pill. Other drugs cannot be absorbed well by the digestive system, so they have to be given in another form. Most kinds of chemotherapy are injected, either into the circulatory system or into other cavities within the body. For some chemotherapy medications, a surgeon will insert special vascular access devices. These give doctors easy access to the circulatory system and allow for chemotherapy to be given without a needle being stuck into the patient's veins each time. These devices (also known as ports) can also let doctors give multiple drugs at once or via a continuous infusion.
Side Effects
As mentioned before, chemotherapy poisons cells that are rapidly dividing. Unfortunately, the medications cannot distinguish between cancer cells which are dividing and healthy cells. As a result, the National Cancer Institute explains, chemotherapy can cause certain side effects. Some of the more common ones are nausea, vomiting, hair loss, mouth sores and decreased numbers of blood cells. The type and severity of the side effects depends on the drugs used and the individual patient. In general, doctors can prescribe medications which can help relieve these side effects.
