Encyclopedia Home / C / Chemotherapy - HealthCentral Encyclopedia


  • Definition

    chemotherapy is the use of drugs or medications to treat disease. The term comes from two words that mean "chemical" and "treatment."


    Most people have had some type of chemotherapy for illness during their lives - for example, taking penicillin for an infection. Today, the word "chemotherapy" is used most often to describe a method of cancer treatment.

    In the early days, chemotherapy was considered a last resort to be used only in terminal cases when all else had failed to cure a cancer. When it was used so late in the disease, there was every reason for pessimism, because the chances were slim that drugs - or anything - could save anyone at the eleventh hour. Chemotherapy was then highly experimental and there were relatively few drugs available for experimentation.

    Today, chemotherapy is being used to achieve goals more optimistic and realistic than those in the past. Chemotherapy is presently being used for a number of purposes:

    • to kill some cancers outright
    • to induce long remissions in some cancers
    • to decrease the likelihood of a recurrence or spreading after surgery or radiation (adjuvant chemotherapy)
    • to slow the growth and alleviate symptoms, such as pain (palliation) in incurable or recurrent cancers
    • to shrink large tumors to operable size
    • to make radiation therapy more effective


    Cancer chemotherapy can consist of one drug or a group of drugs that work together (combination chemotherapy).

    A treatment plan that also includes surgery and/or radiation therapy is called combined modality treatment.

    In adjuvant chemotherapy, anticancer drugs are used (after another treatment) to destroy any cancer cells that may remain after surgery or radiation therapy.

    Chemotherapy has proven very effective in cancer treatment. Cancer cells grow in an uncontrolled manner. They can break away from their original site and spread to other parts of the body. Anticancer drugs disrupt the cancer cells' ability to grow and multiply. Chemotherapy is the only scientifically proven method that can reach virtually every part of the body to seek and destroy cancer cells that surgery and radiation cannot reach and sensitive instruments cannot see. It is able to do this because it circulates throughout the body the same way cancer cells do - by flowing through the bloodstream. Once the drug meets with a cancer cell it wreaks havoc in a number of ways, which are only partly understood.

    Chemotherapy may be given in several ways. Sometimes, the drugs are used to obtain a local effect (for instance, in treating skin cancer). In other cases, chemotherapy is given to achieve a total-body (systemic) effect.

    The best way to get the drug to the cancer site depends on the particular type of cancer and the drug or combination of drugs used. The medicine may be taken by mouth, injected into a muscle or through a vein. Once in the blood, an anticancer drug is carried through the body to reach as many cancer cells as possible. How fast the cells are destroyed may vary with different medicines and different types of cancer.

    Chemotherapy affects the course of cancer by taking advantage of the cancer cell's penchant for constant reproduction. Almost all the drugs used in chemotherapy suppress cancer by somehow altering the cells' DNA, and thus, their ability to reproduce. Since DNA is most vulnerable to drug interference during the reproductive phases of the life cycle, the cancer cells are more likely to be affected than the bulk of the body's normal cells (which reproduce at a more relaxed rate). Thus, the very characteristic that makes cancer so dangerous has proved to contribute to its undoing. In scientific terminology, chemotherapy drugs are either cell-cycle-specific (lethal to cells only during a reproductive phase), or cell-cycle-nonspecific (able to sabotage the cells no matter what phase they are in).

    Anticancer drugs can affect normal tissues also, because they act on any rapidly dividing cells in the body. The normal cells most likely to be affected are those in the bone marrow, gastrointestinal (GI) tract, reproductive system, and hair follicles. Most normal cells are able to recover quickly when the treatment is over.

    Side Effects

    Whether or not there are side effects depends on the particular drug used and individual response to it. There are more than 50 drugs used alone and in various combinations to treat the more than 100 types of cancer. Therefore, it is hard to predict whether a particular patient will have a specific side effect. In fact, you could notice a certain side effect after one treatment and not see the same effect the next time. You should discuss possible side effects with your doctor, nurse or pharmacist. You need to know what to expect from treatment and which side effects may need medical attention.

    Some side effects of chemotherapy (i.e., fatigue and hair loss) may start in the early weeks of treatment and continue through the end of treatment. Others, such as nausea and vomiting, may occur for just a few hours after a treatment. Most side effects of chemotherapy gradually disappear once treatment is stopped and the healthy cells have a chance to grow normally. The unwanted effects of treatment can be unpleasant, but they must be measured against the medicine's ability to destroy the cancer.

    People having chemotherapy can become discouraged, because of the length of the treatment or the side effects that can occur. If you begin to feel unhappy about your therapy or how it's progressing, talk to your doctor or nurse. It may be that your medication or the treatment schedule can be altered. Remember - your doctor will not ask you to continue treatments unless the expected benefits outweigh the problems you may have.

    Some side effects can decrease during treatment as your body adjusts to the therapy. However, you should remember that the time it takes to get over some of the troublesome side effects and regain energy varies from person to person. How soon you feel better depends on many factors, including your condition and the kinds of medicines you have been taking.

    Risk Of Infection

    Most anticancer drugs affect the bone marrow, decreasing its ability to produce blood cells. The white blood cells produced in the bone marrow help to protect your body by fighting bacteria that cause infection. If the number of white cells in your blood is reduced, there is a higher risk of getting an infection. If you have a reduced white cell count, it is very important that you try to prevent infection by taking the following steps:

    • Wash your hands often during the day. Be sure to wash them well before eating and after using the bathroom.
    • Avoid crowds, as well as people who have contagious illnesses (such as chicken pox or flu).
    • Do not tear or cut your nail cuticles. Use cuticle cream and remover instead.
    • To prevent breaks in your mouth, avoid using a hard toothbrush or dental floss. Your doctor, nurse or dentist can suggest ways to clean your mouth gently.
    • To prevent breaks in your skin, use an electric shaver rather than a razor.
    • Do not squeeze or scratch pimples.
    • Take a warm shower every day and lightly pat your skin dry rather than rubbing briskly.
    • If your skin becomes dry and cracked, use lotion or oil to soften and heal it.
    • If you do cut or scrape your skin, clean the area at once with warm water and soap.
    • After each bowel movement, clean the rectal area gently but thoroughly. If there is irritation or if hemorrhoids are a problem, ask your doctor or nurse for advice.

    Control Of Nausea And Vomiting

    Drugs that bind to a specific neurotransmitter receptor appear able to control most cases of chemotherapy-induced nausea and vomiting with minimal side effects. Physicians familiar with these serotonin antagonists are hailing them as a significant advance.

    Until recently, a group of drugs (called phenothiazines) had been the mainstay of antiemetic therapy. The drugs in this class include Compazine, Trilafon and Torecan.

    A whole new class of drugs (serotonin receptor blockers) holds tremendous promise for controlling nausea and vomiting. Ondansetron (Zofran) is the first of this class to be available. For most people, it works well against chemo regimens considered to be the most notorious for causing severe vomiting. Another advantage is it does not cause the drowsiness that most other antiemetics do.


    What chemotherapy drug(s) will you be prescribing?

    What are the side effects?

    How successful is this type of therapy?

    How long will the medication be given?

    Can you explain how this drug works to cure the condition?

    Will this treatment cure or just slow down the disease process?

    What do you recommend to control nausea or other side effects?

    Are there any new experimental drugs being used with promising results?

    Are there any alternative or experimental treatments?