Chemotherapy involves the use of active drugs or chemicals to destroy or damage the cancer cells in the body, often in combinations or intervals. Drugs used in Chemotherapy are sometimes referred to as anticancer agents. The drugs must be toxic enough to kill leukemic cells, which is why Chemotherapy can be rough on your body; the toxicity of the drugs can also affect your healthy cells. Effective Chemotherapy however relies on the fact that the cancer cells are more responsive to the chemicals than regular cells are.

In patients with blood cancers, the improvement in diagnosis and recovery is primarily attributed to the advancement of Chemotherapy drugs over the past 40 years. Today’s leukemia, lymphoma, and myeloma treatments occasionally combine Chemotherapy with Radiation therapy. Very high-dose Chemotherapy can also be used, followed by stem cell transplantation.

The purpose of Chemotherapy is to destroy or kill cancer cells so that there is no evidence of disease (remission) or progression of the disease is slowed down. For many people, Chemotherapy can produce long-term remission or outright cure, depending on the type and extent of the cancer.

Treatment Phases for Acute Myeloid Leukemia (AML) and Acute lymphoblastic leukemia (ALL)

Most patients with AML and ALL usually receive treatment in two phases, or cycles:

Induction therapy

Post-remission, or consolidation, therapy

Induction Therapy

Induction therapy is the first step of both AML and ALL Chemotherapy. Patients with AML and ALL need to start induction therapy immediately. The aim of induction therapy is to “induce,” or promote remission — when there is no diseases evidence left. The induction therapy explicitly aims to:

• Kill as many AML and ALL cells as possible.
• Have blood counts returned to normal?
• Reduce the symptoms for prolonged time.

Patients may need to go through multiple rounds of induction therapy, or cycles, before all leukemia cells are killed. Doctors know the effectiveness of induction therapy when they are unable to see leukemia cells in the blood or marrow. Patients continue feeling better too. This is what is considered to be a remission.

Induction therapy is done at a hospital, where most patients spend four to six weeks completing multiple Chemotherapy cycles. A cycle of Chemotherapy usually consists of one week of taking the drugs followed by several weeks of letting the body heal. Based on patient’s health status, patients who have a full-time caregiver can be discharged sooner.

Post-Remission Therapy

After patients’ complete induction therapy and get into remission, additional therapy is still needed. This second recovery phase is known as post-remission therapy, or consolidation therapy. In this second phase the cancer may probably come back.

Post-remission treatment requires chemotherapy, and often a transplant of stem cells. The aim is to kill the stray leukemia cells that blood or marrow tests do not find. Patients receive post-remission therapy at the hospital or in an outpatient environment for a period of four to six weeks, often longer, depending on the post-remission medication and its side effects.

Doctors decide type of post-remission therapy by looking into:

• Overall health of the patient
• Certain types of changes to the genes in leukemic cells
• The availability of a stem cell donor

Patients who do not undergo stem cell transplantation are usually administered four Chemotherapy cycles. Strong Chemotherapy with high doses of cytarabine or other medications is given for better results.

Maintenance Therapy for ALL

Patients with ALL need a longer duration of post-remission therapy than patients with AML do. A continuing treatment is called maintenance treatment after the initial post-remission therapy, which lasts about two years.

Side effects of Chemotherapy in leukemia.

Chemo drugs can affect some of the body’s normal cells which can lead to side effects. Chemo’s side effects depend on the type and dose of drugs given, and the length of time taken. May include common side effects:

• Hair loss
• Mouth sores
• Loss of appetite
• Nausea and vomiting
• Diarrhea or constipation

Chemo drugs also affect the normal cells in bone marrow, which can lower blood cell counts. This can lead to:

• Increased risk of infections (from having too few normal white blood cells)
• Easy bruising or bleeding (from having too few blood platelets)
• Fatigue and shortness of breath (from having too few red blood cells)

When therapy is over, most side effects from chemo go away. Low counts of blood cells will last for weeks but will return to normal afterwards. There are often ways of lessening the side effects of chemo. Be sure to ask the cancer care team about medications that help mitigate side effects and let the doctor or nurse know when you have side effects so that they can be easily handled.

Side effects of specific drugs: Certain drugs might cause specific side effects. For example:

Cytarabine can cause dryness in the eyes, particularly when used at high doses, and can affect certain parts of the brain, which can lead to coordination and balance problems. Vincristine can damage the nerves, resulting in numbness, tingling or weakness of the hands or feet. Anthracyclines (such as daunorubicin or doxorubicin) can harm the heart, and the overall dosage needs to be carefully monitored, so these medications should not be used in anyone who has heart problems already.

Other organs that certain chemo drugs could damage include the kidneys, liver, testicles, ovaries, and lungs. Doctors and nurses monitor the medication closely to minimize the likelihood of these side effects. When there are severe side effects, the chemo can need to be decreased or halted, at least for a while.

Second cancers: One of the most severe side effects of ALL treatment is an elevated risk of later developing acute myeloid leukemia (AML). This happens in a small proportion of patients after receiving certain chemo-drugs. Less frequently, people who are cured of leukemia can develop non-Hodgkin Lymphoma or other cancers later on. Of course, the possibility of developing these second cancers needs to be weighed against the apparent advantage of using Chemotherapy to treat a life-threatening illness like leukemia.

Tumors lysis syndrome: This side effect of chemo is most common in patients with large numbers of leukemia cells in the body, and it is more commonly seen in the first (induction) treatment process. When leukemia cells are destroyed by chemo, they split open and spill their contents into the bloodstream. This can overload the kidneys, that cannot get rid of all these substances at once. Excess quantities of these substances can affect the heart and nervous system, too. This can also be prevented by giving extra fluids during treatment and by administering certain drugs, such as bicarbonate, allopurinol and rasburicase, that help the body get rid of these substances.