Leukemia is cancer arising from blood-forming cells, mainly in the bone marrow and lymphatic system. The National Cancer Institute, or NCI, estimates that there will be over 43,000 new cases of leukemia in the U.S. in 2010, with nearly 22,000 deaths.
Chemotherapy, or chemo, the use of drugs that destroy cancer cells or stop them from growing and spreading, forms a major part of treatment for most types of leukemia. Chemotherapy treatments for leukemia depend on the type of leukemia, state of health of the patient and clinical stage of the disease.
Induction Chemotherapy
According to the American Cancer Society, or ACS, the goal of induction chemotherapy is to achieve a remission, meaning that there are no more cancer cells in the bone marrow, normal bone marrow cells are seen and the blood count is back to normal. This particular treatment is used in acute leukemias and late stages of chronic leukemias. It involves giving chemotherapy drugs in cycles of days at a time for several months.
The drugs used in induction chemotherapy for acute lymphocytic leukemia, or ALL, are typically a combination of vincristine, dexamethasone or prednisolone, and doxorubicin or daunorubicin. Other drugs that may be added based on the patient’s state of health, according to the ACS, include cyclophosphamide, L-asparaginase, and/or high doses of methotrexate or cytarabine.
Induction chemotherapy for acute myeloid leukemia, or AML, is usually a combination of cytarabine and daunorubicin or idarubicin. According to the ACS, 6-thioguanine may be added in some cases. Elderly or sicklier patients may receive only one drug for induction chemotherapy in AML.
Consolidation or Post-Remission Chemotherapy
This is chemotherapy given after a remission of leukemia to prevent a relapse and destroy any surviving cancer cells in the body, according to the ACS. The drugs used for induction chemotherapy are repeated for a shorter period of time in ALL for consolidation chemotherapy. The treatment typically lasts for a few months.
For AML, consolidation chemotherapy typically involves giving three or four cycles of higher-dose cytarabine alone. For older or sicklier patients with AML, one or two cycles of high-dose cytarabine or a combination of cytarabine and idarubicin or daunorubicin is used.
Maintenance Chemotherapy
In some cases of ALL, according to the ACS, after consolidation, maintenance chemotherapy is required. This usually involves the use of methotrexate and 6-mercaptopurine for a period of two years. Other drugs like vincristine and prednisolone may be added.
Intrathecal Chemotherapy
Intrathecal chemotherapy is the injection of chemotherapy drugs directly into the cerebrospinal fluid to treat or prevent the deposit of cancer cells in the brain or spinal cord, especially in AML. The drugs used for intrathecal chemotherapy are methotrexate with or without cytarabine or a steroid such as prednisolone or hydrocortisone.
Other Chemotherapy Treatments for Leukemia
Where treatment is needed in chronic lymphocytic leukemia, or CLL, fludarabine with or without cyclophosphamide or chlorambucil and/or immunotherapy is used. Other combinations of other cancer drugs may also be used in CLL, like cyclophosphamide, vincristine and prednisolone, the CVP regimen. Other drugs which may be used in combination chemotherapy for leukemia are chlorambucil, bendamustine, pentostatin and cladribine.
Chemotherapy is not commonly used in chronic myeloid leukemia, or CML, except in cases that do not respond to the more conventional treatment with tyrosine kinase inhibitors. The chemotherapy drugs used in CML are hydroxyurea, busulfan, cytarabine, cyclophosphamide and vincristine.
References
- National Cancer Institute: Leukemia
- American Cancer Society: Typical treatment of acute lymphocytic leukemia
- American Cancer Society: Typical treatment of acute myeloid leukemia
- American Cancer Society: Treatment of chronic lymphocytic leukemia by risk group
- American Cancer Society: Treating chronic myeloid leukemia by phase
