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Chronic myelogenous leukemia (CML) is a rare type of cancer of the blood cells. It's considered chronic leukemia because it usually progresses more slowly than acute leukemia, sometimes over the course of years.

Any type of cancer can be frightening, of course. And unfortunately, CML is not a solid tumor that can be surgically removed. But the good news is that the prognosis for people with chronic myelogenous leukemia may be improving because of new medications to treat the condition. Although a bone marrow transplant may still be an option, many people with chronic myelogenous leukemia are able to manage their condition long term with the use of chemotherapy-like pills.

In fact, people can live with this kind of cancer for many years if it goes into remission. But of course, that also means that you must find healthy ways to cope emotionally with having a serious, chronic condition.

Chronic myelogenous leukemia symptoms may vary depending on the stage of the cancer before treatment begins. At its earliest, chronic myelogenous leukemia may not have any signs or symptoms.

Early signs and symptoms
Early signs and symptoms of CML are often vague. They may include:

• Fever
• Losing weight without trying
• Loss of appetite
• Feeling run-down or tired
• Pain or fullness below the ribs on the left side
• Sweating excessively during sleep (night sweats)

More advanced signs and symptoms
More specific signs and symptoms may emerge in the more advanced phases of untreated chronic myelogenous leukemia. These may include:

• Anemia
• Enlarged spleen
• Shortness of breath
• Fatigue
• Pale skin
• Frequent infections
• Easy bleeding
• Bruising
• Pinprick-sized red marks on the skin (petechiae)
• Stroke
• Bone pain
• Joint pain

Medical researchers know more about the development of chronic myelogenous leukemia than virtually any other type of cancer. CML arises from a complex process of mutations involving chromosomes and genes in your blood cells. This is why CML can't be surgically removed — it involves blood cells throughout much of your body.

The Philadelphia chromosome
The process begins with the creation of a mutated chromosome called the "Philadelphia chromosome," named after the city where researchers discovered it in the early 1960s. The abnormal Philadelphia chromosome develops from a translocation, or switching, of material between two previously normal chromosomes. A section of chromosome 9 switches places with a section of chromosome 22. This creates an extra-short chromosome 22 and an extra-long chromosome 9. This extra-short chromosome 22 is called the Philadelphia chromosome. The translocated section on chromosome 22 forms a gene called BCR-ABL. This gene, in turn, produces an abnormal protein called tyrosine kinase that promotes cancer by allowing certain blood cells to grow out of control.

Blood cells originate in the bone marrow. When bone marrow functions normally, it produces immature cells (stem cells) in a controlled way. These cells then mature and specialize into the various types of blood cells — red cells, white cells and platelets. Those then wind up in the blood that circulates throughout your body (peripheral blood). When these blood cells grow old, they die off naturally and are replaced by new cells, in a continuous, healthy cycle.

Abnormal white blood cells
In chronic myelogenous leukemia, this blood cell production process goes awry. The abnormal protein causes the bone marrow to produce far too many white blood cells. Many or all of these white blood cells are considered leukemia cells. That is, they contain the abnormal Philadelphia chromosome. This overproduction of white blood cells is why CML is also considered a type of myeloproliferative disorder, which is a group of conditions characterized by uncontrolled production of one or more types of blood cells.

With chronic myelogenous leukemia, the white blood cells can generally function normally at first. But they don't fully mature and allow new cells to take their place. Over time, the white cells build up in huge numbers and eventually crowd out healthy blood cells. The bone marrow may become damaged and stop producing cells normally. All this leaves people with CML vulnerable to infection, easy bleeding and other life-threatening problems.

In later stages of chronic myelogenous leukemia, the process of disease growth becomes more complex and is less understood. Additional mutations may develop in other chromosomes. And one big mystery remains — what triggers the development of that original Philadelphia chromosome.

Chronic myelogenous leukemia is a rare form of leukemia, affecting only one to two of every 100,000 people. In the United States, about 4,600 people are diagnosed with CML each year. It tends to affect more men than women, and the incidence increases with age. CML rarely occurs in children.

Although researchers know a lot about how chronic myelogenous leukemia develops, little is known about what increases someone's risk of getting this cancer. What is known is that even though CML results from a genetic mutation, the mutation isn't hereditary. That is, it's not passed from parents to children. Rather, it's an acquired genetic mutation that develops spontaneously during the routine process of cell growth.

The only known risk factor
Researchers also know that exposure to very high levels of radiation increases the risk of developing chronic myelogenous leukemia — the only known risk factor for this type of cancer. Survivors of an atomic bomb blast or a nuclear reactor accident are at higher risk of developing chronic myelogenous leukemia.

On the other hand, most people with CML have never been exposed to this level of radiation. So clearly, other factors, though still unknown, are at play. Although most of the research about CML has involved its treatment, researchers are trying to learn more about what triggers the genetic mutation that causes CML.

It's possible to live with chronic myelogenous leukemia for months or in some cases several years without realizing it. In fact, CML is often discovered only by accident, during a routine checkup or a blood test for something else entirely. This form of cancer doesn't always reveal itself with obvious signs and symptoms during the early phase. Some people with early symptoms, such as fatigue, try to ignore the symptoms or blame them on something else, such as overwork.

People with chronic myelogenous leukemia tend to respond better to treatment when it's started early. So be sure to visit your health care professional if you feel run-down or tired, lose weight without trying, sweat excessively during sleep or have other possible signs and symptoms of CML.

Chronic myelogenous leukemia is often discovered unintentionally. Many people, for instance, have a blood test for something else and doctors notice that they have a high white blood cell count, leading to suspicions of leukemia. Other times, people have symptoms that lead them to visit their health care professional.

In either case, certain tests and procedures can help your doctor determine if you have chronic myelogenous leukemia or some other medical problem.

Common diagnostic procedures
Common tests and procedures to diagnose CML include:

• Physical exam. Your doctor will perform a thorough physical exam. This includes a check of such vital signs as pulse and blood pressure, as well as checks of your lymph nodes, spleen and abdomen.
• Complete blood count (CBC). With CML, many of your blood cells may show abnormalities. A CBC is a basic blood test that can show problems with your white cells, red cells and platelets. However, while a CBC can offer good clues about what's wrong and the extent of problems, it isn't a sure way to diagnose CML.
• Bone marrow exam. A bone marrow biopsy and aspiration is the definitive way to diagnose CML. Because it's an invasive and potentially painful exam, it's usually done only after a blood test. A bone marrow exam can reveal whether you have the Philadelphia chromosome and abnormal BCR-ABL gene.
• FISH analysis. This is a specialized blood test that shows changes in the chromosomes and can detect the Philadelphia chromosome. FISH stands for fluorescent in situ hybridization. In rare cases, forms of leukemia other than CML can have the Philadelphia chromosome, so the FISH test may not be a definitive way to diagnose CML. Also, a small percentage of people with CML lack the Philadelphia chromosome, which means other tests are necessary.
• Polymerase chain reaction (PCR). This is a very specialized molecular blood test that can detect the abnormal BCR-ABL gene. This test can be done from a blood sample or a bone marrow sample.
• Imaging tests. Your doctor may order imaging tests, such as an ultrasound or computerized tomography (CT) scan, to determine if any of your organs have been affected. CML often causes the spleen to enlarge, for instance.

Phases of chronic myelogenous leukemia
Chronic myelogenous leukemia is divided into three progressive phases. CML starts in chronic phase, then moves to accelerated phase and finally progresses into blast phase. Moving through the phases signals a worsening of the disease. Identifying which phase of CML you're in is important because it helps determine which type of treatment is best.

Which phase your CML is in depends on such factors as your blood counts, the percentage of immature (blast) cells you have and the size of your spleen. The chronic phase is the earliest phase and generally has the best response to treatment. The blast phase, also know as the acute phase or blast crisis, occurs when CML has transformed to a severe, aggressive phase that becomes life-threatening.

Chronic myelogenous leukemia can cause a variety of complications depending on its phase. Complications can occur either before CML is diagnosed and treated or as a result of the treatment. They include:

• Fatigue. CML can cause you to have too few red blood cells, resulting in anemia. Anemia can make you feel tired and worn down. Treatment for CML can also cause a drop in red blood cells.
• Excess bleeding. Blood cells called platelets help control bleeding by prompting your blood to clot. A shortage of blood platelets (thrombocytopenia) can result in easy bleeding and bruising, including frequent or severe nosebleeds, bleeding from the gums, or tiny red marks caused by bleeding into the skin (petechiae).
• Pain. CML can cause bone pain or joint pain as the bone marrow expands when excess white blood cells build up.
• Enlarged spleen. Some of the extra blood cells produced when you have CML are stored in the spleen. This can cause the spleen to become swollen or enlarged. Rarely, the spleen becomes so large that it's at risk of bursting. More commonly, the swollen spleen takes up space in your abdomen and makes you feel full even after small meals or causes pain on the left side of your body below your ribs.
• Stroke or excess clotting. Some people with CML produce too many platelets. Without treatment, this high platelet count (thrombocytosis) can cause excessive clotting of your blood, which can lead to stroke.
• Infection. White blood cells help the body fight off infection. Although people with CML have too many white blood cells, these cells are often leukemic and don't function properly. As a result, they aren't able to fight infection as well as healthy white cells can. In addition, treatment can cause your white cell count to drop too low (neutropenia), also making you vulnerable to infection.
• Death. If CML can't be successfully treated, it ultimately is fatal.

Many people with chronic myelogenous leukemia are treated by a hematologist, or a doctor who specializes in blood-related disorders. Others may see an oncologist, or a doctor who specializes in cancer. In addition, you may also work with nurses, social workers and other health care professionals.

As with many types of cancer, the treatment of chronic myelogenous leukemia can be challenging. And the decisions you must make about your treatment can be complicated because there are many options, including several newer treatments that are showing promise but that still must be proved over the course of time. The goal of chronic myelogenous leukemia treatment is to eliminate the blood cells that contain the abnormal BCR-ABL gene because this is the gene that causes CML. For most people, treatment won't cure CML but it can help them achieve long-term remission of their disease. This often allows them to live a relatively normal life, even though they may have to cope with medication side effects and frequent medical visits.

Targeted medications
A variety of targeted medications is available to treat chronic myelogenous leukemia. These highly specialized medications are designed to specifically stop the abnormal BCR-ABL gene from working. Two targeted medications that the Food and Drug Administration (FDA) has approved are imatinib mesylate (Gleevec), which has been on the market since 2001, and dasatinib (Sprycel), which came on the market in mid-2006. Although both of these medications are in tablet form, they are powerful cancer medications that can cause serious or life-threatening side effects. Because both of these medications are relatively new, it's too soon to tell if they'll extend survival. However, most CML experts consider these medications vast improvements in CML treatment. In addition, most research has shown that people must continue to take these medications indefinitely, because when they stop the disease may quickly return or progress.

Stem cell transplant
A stem cell transplant, also called a bone marrow transplant, offers the only potential cure for chronic myelogenous leukemia. However, a stem cell transplant is a risky procedure with a high rate of complications, some of which are life-threatening. Stem cell transplants used to be more common for CML because other treatment options were limited. Today, though, a stem cell transplant is typically recommended only after other treatments haven't worked and the disease has continued to progress. But because a stem cell transplant may offer a cure or a long-term remission of the disease, you may face a difficult decision choosing transplant or another type of treatment. In some cases, you may opt to have your own stem cells collected and then stored for future use. This procedure is generally called a stem cell harvest and hold or a stem cell collection. This procedure is generally intended for people who don't have a suitable donor for a stem cell transplant. Instead, your own stem cells are collected when you're in remission, and if your disease later progresses, you may be able to transplant your healthy stem cells back into your body in the hope of achieving another remission.

Chemotherapy
Many people who are newly diagnosed with chronic myelogenous leukemia have a course of chemotherapy to help eliminate the excess white blood cells. Often, this chemotherapy is in tablet form that you can take by mouth. It's usually taken along with other treatments. Chemotherapy can also be used if other treatments don't work and the CML is progressing, or in preparation for a stem cell transplant.

Biological therapy
An injectable medication called interferon alpha used to be the standard treatment for CML. This medication reduces the growth of leukemia cells by stimulating the body's immune system to work better. Interferon is still used for CML when other treatments don't work or when they aren't an option, such as during pregnancy. But interferon also causes significant side effects, including fatigue, bone pain, headaches and vomiting.

Clinical trials
For some people with chronic myelogenous leukemia, standard treatments don't work or cause too many dangerous side effects that can't be controlled with other medications. In such cases, people with CML may choose to join a clinical trial. A clinical trial tests new treatments or new combinations of existing treatments. People who participate in clinical trials have no guarantee that the treatment will help them. In fact, clinical trials are meant more to help people in the future because information about treatment effectivness and side effects is usually collected and analyzed over a period of years.

Very little is known about how to potentially prevent chronic myelogenous leukemia. Because the only known risk factor is exposure to high levels of radiation, preventing that exposure may help prevent CML. However, other methods to prevent chronic myelogenous leukemia aren't known.

Because chronic myelogenous leukemia is rare and treatment options can be complicated, you may want to consider taking an active role in managing your condition. Here are some self-care measures you can take:

• Specialists. If you are treated by a doctor with little or no experience in CML, consider having a consultation with a specialist in the condition, either in person or on the phone, especially if your situation is complicated. Your local doctor may be willing to help arrange a consult.
• Side effects. Be sure to let your health care team know about any side effects you experience from your treatment. Powerful cancer medications can cause many side effects, but those side effects often can be managed with other medications or treatments. You don't necessarily have to tough them out.
• Don't stop treatment on your own. If you develop unpleasant side effects, such as skin rashes or fatigue, don't simply quit your medication without consulting your health care professionals. Likewise, don't stop taking your medications if you feel better and think your disease may be gone. If you stop taking medication, your disease can quickly and unexpectedly return, even if you've been in remission.

When people picture someone with cancer, they may picture someone with visible signs of a horrible disease: A woman who has lost her breast. A man who is too weak to stand. A young mother with a bright scarf covering her bald head. Yet, these images often don't represent the reality of living with chronic myelogenous leukemia.

Many people with CML are stuck with long-term treatments — and the nausea, muscle cramps, fatigue and other side effects they may cause. Here are some tips for coping:

• Get down to particulars. The term "leukemia" can be confusing, because it refers to a batch of cancers that aren't all that similar except for the fact that they affect the bone marrow and blood. You can waste a lot of time researching information that doesn't apply to your kind of leukemia. To avoid that, ask your health care professionals to write down as much information about your specific disease as possible. Then narrow your search for information accordingly, and seek out only trusted, reputable sources. Also, write down questions to ask before each medical appointment.
• Get support. Lean on family and friends, as well as others with CML. It can be tough to talk about your diagnosis, and you'll likely get a range of reactions when you share the news. But talking about your diagnosis and passing along information about your cancer can help. So can the outpouring of practical help that often results. You may also benefit from joining a support group, either in your community or on the Internet. A support group of people with the same diagnosis can be a source of useful information, practical tips and genuine encouragement.
• Explore ways to cope with the chronic nature of the disease. If you have CML, you'll likely face frequent blood work and medical appointments and regular bone marrow exams. Some days, you may feel sick even if you don't look sick. And some days, you may just be sick of having cancer. Try to find some activities that help, whether it's yoga, exercise, social outings or adopting a more flexible work schedule. Talk to a counselor, therapist or oncology social worker if you need help dealing with the emotional toll of this chronic disease.