Chemotherapy uses drugs to destroy cancer cells in the body. A cancer patient generally receives chemotherapy for a specific amount of time, after which the cancer is re-evaluated to determine whether it has been successfully destroyed or whether further treatment is needed. Different types of chemotherapy medications can be tailored to the individual patient and the specific type of cancer, but these drugs do come with a wide range of side effects.
Purpose
According to the National Cancer Institute, chemotherapy serves three related purposes. The first goal is to cure the cancer by destroying cancer cells completely so that they don't return again. If the cancer doesn't respond completely, a secondary goal is to slow the growth of the tumor and prevent it from spreading to other areas of the body. A third purpose of chemotherapy is to make existing tumors smaller, which can ease symptoms associated with the cancer.
Science
Chemotherapy drugs are designed to kill rapidly growing cells. Because many normal cell types in the body, such as bone marrow cells and the cells lining the inside of the mouth, also grow rapidly, chemotherapy also affects these cell types. Doctors try to limit the damage to normal cells, but side effects are common. The specific type and degree of cancer determines which specific choice of chemotherapy drugs will be used for a given individual.
Drugs
Most chemotherapy drugs have specific biological targets within the cancer cells. According to Merck Manuals, the chemotherapy medication Imantinib blocks the formation of blood vessels in cancer cells and inhibits the cell replication cycle. Methotrexate and cyterabine stop the synthesis of tumor DNA. Vincristine prevents cancer cells from dividing. Erlotinib and gefitinib attack the cell surface receptors of cancer cells. Many people receive a combination of a few different chemotherapy drugs.
Process
Patients receiving chemotherapy check into the hospital to undergo the procedure or receive chemotherapy on an outpatient basis at a hospital, clinic or doctor's office. Chemotherapy is given in cycles, the length and duration of which is determined by the particular drug and the characteristics of the individual patient's cancer and overall health. Cycles consist of a period of chemotherapy infusion, during which a patient is given the drugs daily or every few days, followed by a break during which the patient doesn't receive infusions for a few days or weeks.
Delivery
Chemotherapy can be injected directly into a patient's muscles, spinal column or abdominal cavity. The drugs may also be injected directly into the tumor or the arteries feeding the tumor. The most common method for administering chemotherapy is through intravenous infusions, or an IV, according to the Nemours Foundation. In other cases, oral or topical chemotherapy medications can be used.
Side Effects
According to the National Cancer Institute, the most common side effect caused by chemotherapy is fatigue. Chemotherapy may also cause the loss of hair, nausea and vomiting. Skin problems and mouth sores are also common. The side effects caused by chemotherapy typically go away after the patient stops taking the drugs.
