Chemotherapy uses anticancer drugs that are injected into a vein or a muscle, or are taken by mouth. These drugs enter the bloodstream and reach all areas of the body making this treatment very useful for lymphoma. Depending on the type and the stage of the lymphoma, chemotherapy may be used alone or in combination with radiation therapy. In some cases, chemotherapy is given by intrathecal injection (into the spinal fluid) to treat lymphoma cells on the surface of the brain and spinal cord.

There are many drugs that are useful in the treatment of patients with lymphoma. Usually, several drugs are combined. The treatments all have different schedules, but are usually repeated several times in cycles given 3 or 4 weeks apart. Most chemotherapy treatments are given on an outpatient basis (in the doctor's office or clinic or hospital outpatient department), but some require hospital admission. Sometimes a patient may take one chemotherapy combination for several cycles and later be switched to a different one if the first treatment combination does not seem to be working effectively. This is usually determined after retesting or by physical examination (for example, if an enlarged lymph node hasn't shrunk).

Chemotherapy drugs are intended to kill lymphoma cells but they can also damage normal cells. For this reason, some side effects occur. The doctor will try to avoid them with special drugs that are designed to overcome some of these side effects. He or she will also discuss what the patient can do.

These side effects depend on the type and dose of drugs given and the length of time they are taken. Drugs used in cancer chemotherapy specifically attack cells that are rapidly dividing. These drugs are useful because cancer cells spend more of their time dividing and reproducing than normal cells do. However, there are some normal tissues such as the bone marrow, the lining of the mouth and intestines, and the hair follicles which also grow rapidly in order to replace cells that wear out. These rapidly growing normal cells are the ones most likely to be adversely affected by chemotherapy. As a result, a patient may have hair loss, mouth sores, lowered resistance to infection due to low white blood cell counts, easy bruising, and bleeding due to low platelet counts. Loss of appetite, nausea, and vomiting result in part from damage to intestinal cells, but effects of certain drugs on areas of the brain controlling appetite also contribute to these problems. These side effects are temporary and go away after treatment is finished.

There are often ways to lessen these side effects. For example, drugs can be given along with the chemotherapy to prevent or reduce nausea and vomiting. Drugs known as growth factors (G-CSF or GM-CSF for example) are sometimes given to keep the white blood cell counts higher and thus reduce the chance of infection. Another type of growth factor, erythropoietin helps prevent anemia. Drugs have been developed to prevent low platelet counts, but are still considered experimental.

If a patient's white blood cell counts are very low, the risk of infection can be reduced by carefully avoiding exposure to bacteria, fungi, or viruses. Having the patient wear a surgical mask or having visitors wear a mask, a sterile gown, and surgical gloves may be recommended. During this time, patients should be particularly careful about washing hands and avoiding fresh, uncooked fruit and other foods that might carry germs. Patients may be told to avoid contact with children because children are more likely than adults to carry infections. Another effective way to protect patients with low white blood cell counts against infection is treatment with powerful antibiotics. These may be given before signs of infection appear but are usually given at the earliest sign of an infection such as fever.

If platelet counts are very low, the patient may receive platelet transfusions as protection against bleeding. Likewise, fatigue caused by very low red blood cell counts is treated with red blood cell transfusions. White cell transfusions are not practical because these cells exist in such low numbers in the donor blood so there is no way to harvest enough of them to make a difference.

Because many of the side effects of chemotherapy are due to low white blood cell counts, some patients find it helpful to keep track of their counts. If you are interested in this information don't hesitate to ask your doctor or nurse about your blood cell counts and what these numbers mean. You may wish to keep a diary of your treatment and blood counts to help you follow the effects of your treatment.

Tumor lysis syndrome is a side effect of the rapid breakdown of cells during very effective chemotherapy for some bulky lymphomas. When the NHL cells are destroyed, they release normal cellular components in large amounts into the bloodstream, which may affect the kidneys, heart, and nervous system. This condition can be prevented by giving extra fluids and certain drugs, such as sodium bicarbonate and allopurinol, which help the body dispose of these substances.

Organs that could be directly damaged by chemotherapy drugs include the kidneys, liver, testes, ovaries, brain, heart, and lungs. With careful monitoring, such side effects are rare. If serious side effects occur, the chemotherapy may have to be reduced or stopped, at least temporarily. Careful monitoring and adjustment of drug doses is important because some side effects to organs are permanent.

One of the most serious late complications of successful chemotherapy is the possibility of developing leukemia. This affects a small percentage of NHL patients.