Home > Encyclopedia of Nursing & Allied Health > Chemotherapy

Definition

Chemotherapy is the treatment of cancer with anti- cancer drugs.

Purpose

The purpose of chemotherapy is to kill cancer cells. Not only is it often used to treat patients with cancer that has metastasized (spread) from the site in the body where it originated, today chemotherapy can be used to prevent metastasis as well. Chemotherapy destroys cancer cells throughout the body, killing cells that have broken off from the main tumor and traveled through the blood or lymph systems to other parts of the body.

Chemotherapy can cure some types of cancer. In some cases, it is used to slow the growth of cancer cells or to keep the cancer from spreading to other parts of the body. When a cancer has been removed by surgery, chemotherapy may be used to keep the cancer from recurring; this is known as adjuvant therapy. Chemotherapy also can ease the symptoms of cancer, helping some patients to have a better quality of life.

Precautions

There are many different types of chemotherapy drugs. Oncologists (specialists in cancer) determine which drugs are best suited for each patient. This decision is based on the type of cancer, the patient's age, health, and preferences, as well as other drugs the patient is taking. Some patients may not tolerate certain chemotherapy drugs if they have other illnesses such as heart disease, kidney disease, or diabetes.

Chemotherapy, whether administered in the hospital, clinic, or at home, is prepared by the pharmacist. The pharmacy and pharmacy assistants provide and reinforce patient education about common as well as infrequent side effects of chemotherapy. When administered in the hospital, clinic, physician's office, or other treatment setting, it is usually administered by a specially trained nurse, mid-level practitioner (physician assistant of nurse practitioner), or physician.

Description

More than 50 chemotherapy drugs are currently available to treat cancer, and many more are being tested for their ability to destroy cancer cells. Most chemotherapy drugs interfere with the ability of cells to grow or multiply. Although these drugs affect all cells in the body, most useful treatments are more effective against rapidly growing cancer cells. Since chemotherapy affects rapidly growing cells, it often affects cells that normally grow rapidly such as cells in the bone marrow, stomach intestines, and hair follicles. This is why some of the most common side effects of chemotherapy are bone marrow suppression, nausea, vomiting, and hair loss.

Types of chemotherapy drugs

Chemotherapy drugs are classified based on their mechanisms of action (how they work). The main types of chemotherapy drugs are:

• Alkylating drugs kill cancer cells by directly attacking DNA, the genetic material of the genes. Cyclophosphamide is an example of an alkylating drug.
• Antimetabolites interfere with the production of DNA thereby preventing cells from growing and multiplying. An example of an antimetabolite is 5-fluorouracil (5-FU).
• Antitumor antibiotics are made from natural substances such as fungi in the soil. They interfere with important cell functions, including production of DNA and cell proteins. Doxorubicin and bleomycin belong to this group of chemotherapy drugs.
• Plant alkaloids prevent cells from dividing normally. Vinblastine and vincristine are plant alkaloids obtained from the periwinkle plant.
• Steroid hormones slow the growth of some cancers that depend on hormones. For example, tamoxifen is used to treat breast cancers that depend on the hormone estrogen for growth.

Combination chemotherapy

The oncologist decides which chemotherapy drug or combination of drugs will work best for each patient. The use of two or more drugs together often works better than a single drug alone. This is called combination chemotherapy. Scientific studies and clinical research trials of different drug combinations help determine which combinations are most effective for each type of cancer.

How chemotherapy is administered

Chemotherapy is administered in different ways, depending on the drugs to be given and the type of cancer. The prescribed dose depends on several factors, one of which is the patient's body weight.

Chemotherapy may be administered by one or more of the following methods:

• orally
• intramuscular (IM) or subcutaneous injection
• through a catheter or port
• topically

Oral chemotherapy, given by mouth, may be in the form of a pill, capsule, or liquid. This is the easiest method of administration and can usually be done at home.

Intravenous (IV) chemotherapy is injected into a vein. A small needle is inserted into a vein on the hand or lower arm. The needle is usually attached to a small tube called a catheter, which delivers the drug to the needle from an IV bag or bottle.

Intramuscular (IM) chemotherapy is injected into a muscle. Chemotherapy given by intramuscular injection is absorbed into the blood more slowly than IV chemotherapy. Because of this, the effects of IM chemotherapy may last longer than chemotherapy given intravenously. Chemotherapy may also be injected subcutaneously (under the skin). Injection of chemotherapy directly into the cancer is called intralesional injection.

Chemotherapy may also be given by a catheter or port permanently inserted into a central vein or body cavity. A port is a small reservoir or container that is placed in a vein or under the skin in the area where the drug will be administered. These methods eliminate the need for repeated injections and may allow patients to spend less time in the hospital while receiving chemotherapy. A common location for a permanent catheter is the external jugular vein in the neck. Intraperitoneal (IP) chemotherapy is administered into the abdominal cavity through a catheter or port. Chemotherapy administered by catheter or port into the spinal fluid surrounding the brain or spine is called intrathecal (IT) administration. Catheters and ports may also be placed in the chest cavity, bladder, or pelvis, depending on the location of the cancer to be treated.

Topical chemotherapy is given as a cream or ointment applied directly to the cancer. It may be used to treat certain types of skin cancer.

Treatment location and schedule

Patients may take chemotherapy at home, in the physician's office, or as an inpatient or outpatient at the hospital. Many patients stay in the hospital when first beginning chemotherapy, so they can be observed and monitored for any side effects.

The frequency and duration of chemotherapy given depends on the type of cancer, the patient response to the drugs, patients' overall health and ability to tolerate the drugs, and on the types of drugs used. Chemotherapy administration may take only a few minutes or may last as long as several hours. Chemotherapy may be given daily, weekly, or monthly. A rest period may follow a course of treatment before the next course begins. In combination chemotherapy, more than one drug may be given at the same time, or they may be given alternately, one following the other.

Preparation

A number of medical tests are performed before chemotherapy is started. The oncologist will determine the extent to which the cancer has spread from the results of x rays and other imaging tests and from biopsies. Radiologic technologists and technicians perform imaging studies. Analysis of the biopsy will be performed by a pathologist, assisted by laboratory technicians.

Blood tests, drawn by laboratory technicians or nurses, provide important information about the function of the blood cells and levels of chemicals in the blood. A complete blood count (CBC) is commonly performed before and on a regular basis during treatment. The CBC shows the numbers of white blood cells, red blood cells, and platelets in the blood. Because chemotherapy affects the bone marrow, where blood cells are made, levels of these cells often drop during chemotherapy. The white blood cells and platelets are most likely to be affected by chemotherapy. A drop in the white blood cell count means that the immune system may not function prop- erly and the patient may become prone to infection. Low levels of platelets may cause a patient to bleed from minimal trauma or even spontaneously with no trauma. A low red blood cell count can lead to anemia (deficiency of red blood cells) and fatigue.

Sometimes, patients taking chemotherapy drugs known to cause nausea are given antiemetics before chemotherapy is administered to lessen feelings of nausea. Two anti-nausea medications that may be used are Kytril and Zofran.

Patients may also be advised to prepare for chemotherapy and reduce nausea by eating and drinking normally until about two hours before a chemotherapy session. They should eat high carbohydrate, low-fat foods and avoid spicy foods.

Aftercare

Patient education about how to control side effects after chemotherapy includes:

• Encouraging patients to adhere to instructions given by their health care team.
• Reinforcing correct use of all prescribed medications.
• Advising patients to eat small amounts of bland foods and drink lots of fluids.
• Instructing patients to get plenty of rest.

Some patients find that breathing fresh air or mild exercise, such as walking, helps to relieve the stress and side effects associated with chemotherapy.

Complications

Chemotherapy drugs are toxic to normal cells as well as cancer cells. Doses that will destroy cancer cells will likely cause damage to some normal cells. Physicians adjust (titrate) doses to do the least amount of harm possible to normal cells. Some patients feel few or no side effects, and others may experience more serious side effects. In some cases, a dose adjustment is all that is needed to reduce or stop a side effect.

Some chemotherapy drugs have more side effects than others. The most common side effects include:

• nausea and vomiting• loss of appetite
• hair loss (alopecia)
• anemia and fatigue
• infection
• easy bleeding or bruising
• sores in the mouth and throat
• neuropathy and other damage to the nervous system
• kidney damage

Nausea and vomiting are common, but can usually be controlled by taking antinausea drugs, drinking enough fluids, and avoiding spicy foods. Loss of appetite may be due to nausea or the stress of undergoing cancer treatment. Also, although some chemotherapy drugs cause alopecia, it is almost always temporary and reversible.

Low blood cell counts caused by the effect of chemotherapy on the bone marrow can lead to anemia, infections, and easy bleeding and bruising. Patients with anemia have too few red blood cells to deliver oxygen and nutrients to the body's tissues. Anemic patients feel tired and weak. If red blood cell levels fall too low, a blood transfusion may be given.

Patients receiving chemotherapy are more likely to get infections because white blood cells are reduced. It is important to take measures to avoid infections. When the white blood cell count drops too low, the physician may prescribe medications called colony-stimulating factors that help white blood cells grow. Neupogen and Leukine are two colony stimulants used as treatments to help fight infection.

Platelets are blood particles that make the blood clot. When patients do not have enough platelets, they may bleed or bruise easily, even from small injuries. Patients with low blood platelets should be advised to take precautions to avoid injuries. Medicines such as aspirin and other pain relievers can impair platelet function and slow the clotting process.

Chemotherapy can cause irritation and dryness in the mouth and throat. Painful sores may form that can bleed and become infected. Patients should be advised about actions they might take to prevent or reduce mouth irritation. Precautions to avoid this side effect include dental care before chemotherapy begins, brushing the teeth and gums regularly with a soft brush, and avoiding mouth- washes that contain salt or alcohol.

Results

The primary goal of chemotherapy is to cure cancer. Some cancers, such as Hodgkin's disease and acute lymphocytic

leukemia, may be cured by chemotherapy. Used as adjuvant therapy, in combination with surgery, it may prevent a cancer from spreading to other parts of the body. Some widespread, fast-growing cancers are more difficult to treat. In these cases, chemotherapy may slow the growth of the cancer cells.

Physicians determine the extent to which chemotherapy is effective by closely monitoring the results of medical tests. Physical examination, blood tests, and imaging studies are used to monitor and assess the effects of treatment on the cancer.

The outcomes of chemotherapy include:

• Complete remission or complete response. The cancer completely disappears. The course of chemotherapy is completed, and the patient is tested regularly for a recurrence.
• Partial remission or partial response. The cancer shrinks in size but does not disappear. The same course of chemotherapy may be continued, or a different combination of drugs may be tried.
• Stabilization. The cancer does not grow or shrink. Other therapy options may be explored. A tumor may remain stabilized for many years.
• Progression. The cancer continues to grow. Other therapy options may be explored.
• A new type of malignancy may develop, and this secondary cancer may require additional chemotherapy or other treatment.

Health care team roles

Patients with cancer are usually cared for by a multidisciplinary team of health professionals. The patient's family physician or primary care physician collaborates with other specialists, such as surgeons and oncologists. Radiologic technicians perform imaging studies, and nurses and laboratory technicians may obtain samples of blood, urine, and other laboratory tests.

Before and after chemotherapy, nurses explain the goals and effects of drug treatment and help to prepare patients and families. Depending on the treatment plan, cancer patients may also benefit from rehabilitation therapy with physical therapists, nutritional counseling from dieticians, and counseling from social workers or other mental health professionals.

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KEY TERMS

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Adjuvant therapy—Treatment given after surgery or radiation therapy to prevent the cancer from coming back.

Alkaloid—A type of chemical commonly found in plants and often having medicinal properties.

Alykylating drug—A drug that kills cells by direct- ly damaging DNA.

Antiemetic—A medicine that helps control nausea; also called an anti-nausea drug.

Antimetabolite—A drug that interferes with a cell's growth or ability to multiply.

Platelets—Blood cells that function in blood clotting.

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Barbara Wexler, M.P.H.