What is Chemotherapy?
Last Modified: November 1, 2001
Chemotherapy is the use of medications or chemicals with cancer-fighting abilities. This why chemotherapy is often called an anti-cancer agent.
It all begins with normal cells versus cancer cells. Normal, healthy cells divide and grow in a patterned, controlled behavior. As they divide, replicas are produced. Cancer cells, on the other hand, grow out of control.
There is no apparent pattern at all. When in contact with a normal cell, the cancer cell takes over and copies itself many times over. In this way, the body becomes overburdened with cancer cells. Chemotherapy destroys cancer cells with drugs.
How does Chemotherapy Work?
Chemotherapy drugs interfere with the cancer cells' ability to grow or multiply. Different groups of drugs act on cells in different ways. Identification of the type of disease is important because certain chemotherapies work best for certain diseases. For example, a patient treated for acute myelogenous leukemia is treated with different agents than one treated with Hodgkin's disease. Even patients diagnosed with the same disease may be treated with different agents, depending on what is known to be most effective for the particular circumstances.
Chemotherapy can damage normal cells as well as cancer cells. Those normal cells most effected are ones which divide rapidly. These include the hair follicles, cells in the gastrointestinal (GI) tract, and bone marrow. Consequently, side effects can occur including: hair loss, mouth sores, difficulty in swallowing, nausea, vomiting, constipation, diarrhea, infection, anemia, and increase risk of bleeding. These side effects will be discussed in greater detail later.
How is Chemotherapy Given?
Chemotherapy can be given in different ways. The five most common methods are:
- intravenous (IV)
- oral (PO)
- intramuscular (IM)
- intrathecal (IT)
- intraperitoneal (IP)
The intravenous route or IV is a very common way of giving medicine directly into a vein. A small plastic needle is inserted into one of the veins in the lower arm. There is some discomfort during insertion because a needle stick is required to get into the vein. After that, the administration of the medication is usually painless.
Chemotherapy flows from the IV bag/bottle, through the needle and catheter into the bloodstream. Sometimes a syringe is used to "push" the chemotherapy through the tubing.
The oral method takes the form of either a pill, capsule or liquid taken by mouth. This is the easiest and most convenient method and can usually be done at home. Under certain special circumstances, chemotherapy given by other routes may also be administered at home.
Intramuscular means that the chemotherapy is given by way of an injection into the muscle. There is a slight sting as the needle is placed into the muscle of the arm, thigh or buttocks. Although, this procedure only lasts a few seconds, the effect of the intramuscular chemotherapy may last much longer. This is because the chemotherapy may be absorbed slowly through the muscular tissues and into the bloodstream.
Certain forms of cancer have a tendency to spread to the nervous system. To treat cancer that spreads to the spinal cord or brain, doctors may perform a spinal tap and inject chemotherapy into the spinal fluid. This is known as the intrathecal method of administration.
Permanent and Temporary Catheters
For some patients, IV insertions can eventually damage the veins in the arm. Some patients have small veins and some have very few accessible veins. Frequent IV insertions and too small or too few veins may prompt the doctor to recommend a permanent type of IV catheter. Permanent catheters allow patients to go home and receive chemotherapy without needing other IV's placed. Along with receiving chemotherapy and IV fluids through this catheter, patients can receive blood products and even have their blood drawn without painful needle sticks.
A common type of permanent catheter is the "Hickman" catheter. The terms "Broviac" or "Groshong" refer to a similar type of catheter made by different manufacturers. All work in similar ways.
Care of these catheters may be a little different, but the principle of insertion is similar. A thin, flexible tube is inserted into one of the central veins, commonly the external jugular vein. While under general or local anesthesia, the tube is tunneled through surface skin tissue between the neck and shoulder to another separate incision, usually on the chest or stomach wall. The entrance site will have stitches and a small bandage to facilitate healing. The exit site for the catheter is easy to see and care for, and patients must change their dressings regularly to prevent infection.
Frequent heparin flushes -- washing out the device with an anti-clotting drug -- are required to prevent blockage. Many patients learn to care for their catheter while in the hospital. Thorough teaching to patients and their families is done before discharge.
Another type of permanent catheter to a central vein is known as the implanted intravenous port. It is round in shape and is surgically inserted under the skin surface of the chest wall, between the neck and shoulder area. A nurse will insert a needle through the top skin surface to access the vein. The chemotherapy can then be given through the catheter as if it were an IV in the arm. As with the Hickman catheter, blood can be removed and received through this device. Although, there is no home care required, periodic heparin flushes are necessary.
There is also a temporary access device for administering chemotherapy that works in the same way as the Hickman catheter, but is removed before the patient is discharged. This is called the multi-lumen catheter because there are three IV lines in one plastic catheter line. Insertion is performed in the patient's room, with local numbing medication injected around the insertion site. Located near the neck, the site is kept covered with a dressing.
Intrathecal chemotherapy can be given into the spinal canal or through an Omaya reservoir. This device is surgically inserted under the scalp for direct injection of chemotherapy throughout the spinal fluid. The drugs are then given through the reservoir, rather than through the back during a spinal tap.
Lastly, chemotherapy may be given via an intraperitoneal (IP) port. This device is similar to the previously mentioned implanted intravenous port. The IP port sits under the skin and requires no specific home care. The port allows for placing chemotherapy directly into the peritoneal (i.e. abdominal) cavity. This technique is used to increase the concentration of the chemotherapy that contacts tumors in the abdomen.