Chemotherapy

Chemotherapy is the use of anti-cancer drugs that are injected into a vein, into a muscle, under the skin, or into the cerebrospinal fluid (CSF), or are taken by mouth to destroy or control cancer cells. Except when given into the CSF, these drugs enter the bloodstream and reach all areas of the body, making this treatment useful for cancers such as leukemia that has spread throughout the body.

Doctors give chemotherapy in cycles, with each period of treatment followed by a rest period to allow the body time to recover. Because of its potential side effects, chemotherapy is sometimes not recommended for patients in poor health, but advanced age by itself is not a barrier to getting chemotherapy.

Chemotherapy for ALL uses a combination of several anti-cancer drugs given over a long period of time (usually about 2 years). The most commonly used drugs include:

• vincristine (Oncovin)
• daunorubicin, also known as daunomycin (Cerubidine)
• doxorubicin (Adriamycin)
• cytarabine, also known as cytosine arabinoside or ara-C (Cytosar)
• L-asparaginase (Elspar), PEG-L-asparaginase (pegaspargase, Oncaspar)
• etoposide (VePesid, others)
• teniposide (Vumon)
• 6-mercaptopurine (Purinethol)
• methotrexate
• cyclophosphamide (Cytoxan)
• prednisone (numerous brand names)
• dexamethasone (Decadron, others)

Possible side effects

Chemotherapy drugs work by attacking cells that are dividing quickly, which is why they work against cancer cells. But other cells in the body, such as those in the bone marrow, the lining of the mouth and intestines, and the hair follicles, also divide quickly. These cells are also likely to be affected by chemotherapy, which can lead to side effects.

The side effects of chemotherapy depend on the type and dose of drugs given and the length of time they are taken. These side effects may include:

• hair loss
• mouth sores
• loss of appetite
• nausea and vomiting
• increased risk of infections (due to low white blood cell counts)
• easy bruising or bleeding (due to low blood platelets)
• fatigue (due to low red blood cells)

These side effects are usually short-term and go away once treatment is finished. There are often ways to lessen these side effects. For example, drugs can be given to help prevent or reduce nausea and vomiting. Be sure to ask your doctor or nurse about medicines to help reduce side effects, and let him or her know when you do have side effects so they can be managed effectively.

Drugs known as growth factors (G-CSF and GM-CSF, for example) are sometimes given to increase the white blood cell counts during chemotherapy to reduce the chance for infection. Because they may hasten the recovery of the white blood cell count and do not seem to cause any harm, they are often used during chemotherapy in patients with ALL.

If your white blood cell counts are very low during treatment, you can help reduce your risk of infection by carefully avoiding exposure to germs. During this time, your doctor may tell you to:

• Wash your hands often.
• Avoid fresh, uncooked fruits and vegetables and other foods that might carry germs.
• Avoid fresh flowers and plants because they may carry mold.
• Make sure other people wash their hands when they come in contact with you.
• Avoid large crowds and people who are sick (wearing a surgical mask offers protection in these situations).

Antibiotics may be given before there are signs of infection or at the earliest sign that an infection may be developing. Drugs that help prevent viral and fungal infections may also be given.

Many of the side effects of chemotherapy are caused by low white blood cell counts. Some people find it helpful to keep track of their counts. If you are interested in this, ask your doctor or nurse about your blood cell counts and what these numbers mean.

If your platelet counts are low, you may be given drugs or platelet transfusions to help protect against bleeding. Likewise, shortness of breath and extreme fatigue caused by low red blood cell counts may be treated with drugs or with red blood cell transfusions.

Tumor lysis syndrome is another possible side effect of chemotherapy. It can be seen in patients who had large numbers of leukemia cells in the body before treatment. When chemotherapy kills these cells, they break open and release their contents into the bloodstream. This can overwhelm the kidneys, which aren't able to get rid of all of these substances at once. Excess amounts of certain minerals may also affect the heart and nervous system. This can be prevented by giving extra fluids during treatment and by giving certain drugs, such as bicarbonate, allopurinol, and rasburicase, which help the body get rid of these substances.

Some possible side effects are specific to certain drugs. For example, cytarabine (ara-C) can cause certain problems, especially when used at high doses. These can include dryness in the eyes and effects on certain parts of the brain, which can lead to coordination and balance problems.

Other organs that could be directly damaged by chemotherapy drugs include the kidneys, liver, testicles, ovaries, brain, heart, and lungs. Doctors and nurses carefully monitor treatment to reduce the risk of these side effects as much as possible.

If serious side effects occur, the chemotherapy may have to be reduced or stopped, at least for a short time. Careful monitoring and adjustment of drug doses are important because some side effects can be permanent.

One of the most serious side effects of ALL therapy is an increased risk of getting acute myelogenous leukemia (AML) at a later time. This occurs in about 5% of patients after they have received chemotherapy drugs called epipodophyllotoxins (etoposide, teniposide) or alkylating agents (cyclophosphamide, chlorambucil). Less often, people cured of leukemia may later develop non-Hodgkin lymphoma or other cancers. Of course, the risk of getting these second cancers must be balanced against the obvious benefit of treating a life-threatening disease such as leukemia with chemotherapy.