Chemotherapy for Chronic Myeloid Leukemia

Chemotherapy (chemo) is the use of anti-cancer drugs that are injected into a vein or taken by mouth. These drugs enter the bloodstream and reach all areas of the body, making this type of treatment useful for cancers that spread throughout the body, like chronic myeloid leukemia (CML). Any drug used to treat cancer (including tyrosine kinase inhibitors or TKIs) can be considered chemo, but here chemo is used to mean treatment with conventional cytotoxic (cell-killing) drugs that mainly kill cells that are growing and dividing rapidly.

Chemo was once one of the main treatments for CML. It's seldom used now because TKIs like imatinib (Gleevec^®) work much better. Today, chemo may be used to treat CML when the TKIs have stopped working. It's also used as part of a stem cell transplant.

Chemo drugs used to treat CML

The chemo drug hydroxyurea (Hydrea^®) is taken as a pill, and can help quickly lower very high white blood cell counts and shrink an enlarged spleen. Other drugs sometimes used include cytarabine (Ara-C), busulfan, cyclophosphamide (Cytoxan^®), and vincristine (Oncovin^®).

Omacetaxine (Synribo^®) is a chemo drug that was approved to treat CML that's resistant to TKIs and progresses to the accelerated phase. It can also help some patients whose CML has developed the T315I mutation that keeps most TKIs from working (discussed in the section about targeted therapy).

Side effects of chemotherapy

Chemo drugs work by attacking cells that divide 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 chemo, which can lead to side effects.

Possible side effects depend on the type and dose of drugs given and how long they are taken. Some common side effects of chemo include:

• Hair loss
• Mouth sores
• Loss of appetite
• Nausea and vomiting
• Low white blood cell counts (leukopenia), which increases the risk of serious infection
• Low blood platelet counts (thrombocytopenia), which can lead to easy bruising or bleeding
• Low red blood cell counts (anemia), which can lead to feeling tired and weak

Still, different drugs can have different side effects. For example, vincristine can cause nerve damage (neuropathy) leading to numbness, tingling, or even pain or weakness in the hands or feet. Lung damage from busulfan is rare, but can be severe. Before starting treatment, speak with your health care team about the drugs you'll get and their possible side effects. Most side effects last a short time and go away once treatment is over, but some can be permanent.

While getting treatment, be sure to tell your cancer care team about any side effects you have. There may be ways to treat them or keep them from getting worse. For instance, there are drugs that work well to prevent or reduce nausea and vomiting.

For information on infections and how to avoid them, see Infections in People With Cancer.

If your platelet counts are very low, you may be given platelet transfusions to help protect against bleeding. Likewise, if low red blood cell counts are causing problems (like shortness of breath and/or weakness), you may be treated with red blood cell transfusions.