Myelogenous Leukemia

What is myelogenous leukemia?

Myelogenous leukemia, also called myeloid leukemia, is a cancer of the blood and bone marrow. Bone marrow is the soft, spongy tissue inside bones where blood cells are made. In healthy marrow, immature cells called myeloid stem cells develop into red blood cells (which carry oxygen), platelets (small cell fragments that help blood clot), and several kinds of white blood cells (which fight infection). In myelogenous leukemia, this process goes wrong. Abnormal myeloid cells multiply out of control, crowd out normal blood cells, and may spill into the bloodstream and settle in other organs such as the spleen and liver.

There are two main forms. Acute myelogenous leukemia (AML) develops quickly, over days or weeks, and involves very immature cells called blasts that cannot do the work of normal blood cells. Chronic myelogenous leukemia (CML) usually develops slowly, often over months or years, and the abnormal cells are more mature and can partly function at first. Because the two forms behave so differently, they are diagnosed, treated, and followed in different ways, and it is important to know which one a doctor is referring to.

Myelogenous leukemia can affect people of any age, but both AML and CML become more common with increasing age, and most people are diagnosed in later adulthood. AML is the most common type of acute leukemia in adults, while CML is rare in children. Men are affected slightly more often than women. In hospital settings the condition is usually managed by hematologists (doctors who specialize in blood disorders) working together with a cancer care team; at Acibadem, for example, care is coordinated through the Medical Oncology Department.

Myelogenous leukemia symptoms

Many myelogenous leukemia symptoms happen because the bone marrow is no longer producing enough normal blood cells. Too few red blood cells causes anemia (a shortage of oxygen-carrying cells), too few platelets leads to bleeding and bruising, and too few working white blood cells makes infections more likely. Common symptoms include:

• Persistent tiredness or weakness that does not improve with rest
• Shortness of breath during ordinary activity
• Pale skin
• Frequent or unusually severe infections
• Fever or night sweats without an obvious cause
• Easy bruising, nosebleeds, bleeding gums, or tiny red or purple spots on the skin (petechiae)
• Unexplained weight loss or loss of appetite
• Bone or joint pain
• A feeling of fullness or discomfort under the left ribs, caused by an enlarged spleen
• Swollen lymph nodes, although this is less common than in other types of leukemia

In AML, symptoms tend to appear suddenly and worsen quickly, often over a few weeks. People frequently describe a flu-like illness that does not go away. Some subtypes of AML cause bleeding or clotting problems early on, and in some cases leukemia cells collect in the gums or skin, producing swelling or lumps.

In CML, symptoms are often mild or absent in the early, or chronic, phase, and the disease is frequently discovered by chance when a blood test is done for another reason. If CML is not treated, it may progress over time through an accelerated phase to a blast phase (sometimes called blast crisis), which behaves like acute leukemia and causes more severe symptoms. It is worth stressing that none of these symptoms is specific to leukemia; most are far more often caused by other, less serious conditions, which is why medical testing is needed to find the cause.

Causes and risk factors

Myelogenous leukemia causes are not fully understood. What is known is that the disease begins when the DNA (the genetic material) inside a myeloid stem cell is damaged or changed. These changes, called mutations, are usually acquired during a person’s lifetime rather than inherited. The altered cell keeps dividing when it should stop, does not mature properly, and its copies gradually take over the marrow.

In CML, the underlying cause is unusually well defined. Almost all people with CML have an abnormal chromosome called the Philadelphia chromosome, which forms when pieces of chromosomes 9 and 22 swap places. This swap creates an abnormal gene, BCR-ABL, which produces a protein that constantly signals the cells to grow. Why this rearrangement occurs in a particular person is usually unknown.

In AML, many different mutations can be involved, and the specific combination influences how the disease behaves and how it is treated. Factors that can raise the risk of developing myelogenous leukemia include:

• Older age
• Previous chemotherapy or radiation therapy for another cancer (known as therapy-related leukemia)
• Exposure to high doses of ionizing radiation
• Long-term exposure to certain industrial chemicals, particularly benzene
• Smoking, which has been linked to a higher risk of AML
• Pre-existing blood disorders such as myelodysplastic syndromes or myeloproliferative neoplasms, in which the marrow already produces abnormal cells
• Certain inherited genetic conditions, such as Down syndrome, Fanconi anemia, and some rare familial syndromes
• Male sex, which carries a slightly higher risk

Having one or more risk factors does not mean a person will develop leukemia, and many people who are diagnosed have no identifiable risk factor at all. Myelogenous leukemia is not contagious and cannot be passed from one person to another.

Myelogenous leukemia diagnosis

A myelogenous leukemia diagnosis is made by examining blood and bone marrow, never on symptoms alone. The process usually begins with a medical history and a physical examination, during which the doctor may look for pale skin, bruising, an enlarged spleen or liver, and swollen lymph nodes. The following tests are then typically used:

• Complete blood count (CBC): a routine blood test that measures the numbers of red cells, white cells, and platelets. In leukemia the white cell count is often very high or occasionally very low, while red cells and platelets are frequently reduced.
• Peripheral blood smear: a drop of blood examined under a microscope to look for immature or abnormal-looking cells.
• Bone marrow aspiration and biopsy: a needle is used, usually under local anesthetic, to draw a small sample of liquid marrow and a thin core of bone from the back of the hip. This is the key test for confirming the diagnosis and identifying the type of leukemia.
• Flow cytometry (immunophenotyping): a laboratory method that identifies proteins on the surface of the leukemia cells, confirming that they are myeloid rather than lymphoid in origin.
• Cytogenetic and molecular testing: analysis of the chromosomes and genes in the leukemia cells. For CML this detects the Philadelphia chromosome or the BCR-ABL gene; for AML it identifies mutations that help predict how the disease will respond to treatment.
• Additional blood tests: checks of kidney and liver function, blood clotting, and uric acid levels, which help the team plan safe treatment.
• Lumbar puncture (spinal tap): in selected cases of AML, a sample of the fluid around the spinal cord is tested to see whether leukemia cells have reached the nervous system.
• Imaging: scans such as ultrasound, chest X-ray, or CT are not needed to diagnose leukemia, but they may be used to measure the spleen, look for infection, or check the heart before treatment.

Doctors use internationally agreed criteria to classify the disease. AML is generally diagnosed when blasts make up 20 percent or more of the cells in the marrow or blood, or when certain specific genetic abnormalities are found regardless of the blast count. CML is confirmed by demonstrating the BCR-ABL gene or Philadelphia chromosome. Unlike solid tumors, leukemia is not given a numbered stage; instead, AML is grouped by subtype and genetic risk category, and CML is described as being in the chronic, accelerated, or blast phase.

Myelogenous leukemia treatment options

Myelogenous leukemia treatment options depend on whether the disease is acute or chronic, its subtype and genetic features, the phase of the disease, and the person’s age and general health. Treatment is planned by a team that may include hematologists, oncologists, transplant specialists, specialist nurses, pharmacists, and supportive care staff. Observation without treatment is generally not appropriate for AML, and CML is also usually treated soon after diagnosis, although the pace and intensity differ considerably between the two.

Treatment of acute myelogenous leukemia

Chemotherapy, meaning drugs that kill rapidly dividing cells, is the mainstay of AML treatment. It is usually given in phases. Induction therapy aims to clear leukemia cells from the blood and marrow and achieve a remission, in which no disease can be detected by standard tests. Consolidation therapy follows to destroy any remaining hidden cells and reduce the risk of relapse. Intensive chemotherapy typically requires a hospital stay of several weeks because blood counts fall sharply before recovering.

Newer targeted therapies are drugs designed to block specific abnormal proteins produced by particular mutations; where such a mutation is present, a targeted drug may be added to chemotherapy or used on its own. For older people or those with other health problems who may not tolerate intensive treatment, lower-intensity drug combinations are often used. One subtype, acute promyelocytic leukemia, is treated differently from other forms of AML, with drugs that encourage the abnormal cells to mature rather than with standard chemotherapy alone.

An allogeneic stem cell transplant, in which the patient’s marrow is replaced with blood-forming stem cells from a donor after high-dose treatment, may be recommended for people whose AML has a higher risk of returning, or whose disease has relapsed. Transplant carries significant risks and is offered only after careful assessment of fitness and donor availability.

Treatment of chronic myelogenous leukemia

The treatment of CML changed dramatically with the introduction of tyrosine kinase inhibitors (TKIs), oral medicines that block the protein made by the BCR-ABL gene. Most people in the chronic phase are treated with a TKI taken daily, usually for many years. Response is monitored with regular blood tests that measure the amount of BCR-ABL in the blood; if the response is inadequate or side effects are troublesome, the doctor may switch to a different TKI. A small proportion of people who achieve a very deep and long-lasting response may, under close supervision, be able to attempt stopping treatment, but this is a decision made with the specialist team and requires frequent monitoring.

For CML that does not respond to TKIs, or that has progressed to the accelerated or blast phase, treatment may include chemotherapy similar to that used for AML and consideration of a stem cell transplant.

Supportive care and recovery

Supportive care is an essential part of all treatment plans. It may include transfusions of red cells or platelets, antibiotics and antifungal medicines to prevent or treat infections, and drugs to control nausea. Surgery has little role in treating leukemia itself, apart from placing a central venous line for giving medicines or, rarely, removing a very enlarged spleen. Rehabilitation after intensive treatment can involve physical therapy to rebuild strength, dietary advice, and psychological support. Some people may be offered participation in a clinical trial, which tests new approaches under strict supervision.

Living with myelogenous leukemia and outlook

The outlook for myelogenous leukemia varies widely and depends heavily on the type of disease. For CML in the chronic phase, TKI therapy allows many people to keep the disease under control for many years, and in many cases life expectancy approaches that of the general population, provided medication is taken consistently and monitoring continues. AML remains a serious illness; many people achieve remission with treatment, but the chance of the disease returning depends on age, general health, and the genetic features of the leukemia cells. Your doctor can explain what is known about your particular situation, but no one can promise a specific outcome.

Living with this condition often means adjusting to regular hospital visits, blood tests, and medication routines. Fatigue is common during and after treatment and may take months to improve. Because the immune system can be weakened, people are usually advised to take precautions against infection, to keep vaccinations up to date as recommended by their team, and to report fevers promptly. Long-term side effects of some treatments, such as effects on the heart or fertility, are discussed before treatment starts wherever possible. Emotional support, whether from family, counselors, or patient groups, is an important part of care, and many people find it helpful to plan gradual returns to work and normal activities rather than expecting an immediate recovery.

Frequently asked questions

What is the difference between myelogenous leukemia and lymphocytic leukemia?

The difference lies in which type of blood cell becomes cancerous. Myelogenous leukemia starts in myeloid cells, which normally develop into red cells, platelets, and most white cells. Lymphocytic (or lymphoblastic) leukemia starts in lymphoid cells, which develop into lymphocytes, a specific kind of white blood cell. The two groups are treated differently, so laboratory testing to tell them apart is a routine part of diagnosis.

Are myelogenous leukemia symptoms different in children?

Children with AML tend to have the same general symptoms as adults, such as tiredness, pallor, fever, bruising, and bone pain, although they may find it harder to describe how they feel, and parents often first notice unusual paleness or irritability. CML is rare in children. Any persistent unexplained symptoms of this kind in a child should be assessed by a doctor, although in most cases the cause is something other than leukemia.

Is myelogenous leukemia hereditary?

In most cases, no. The genetic changes that cause myelogenous leukemia are usually acquired in a single bone marrow cell during life and are not passed on to children. A small number of families carry inherited conditions that increase the risk, and a doctor may suggest genetic counseling if several close relatives have had blood cancers or if the leukemia appears at an unusually young age.

Can myelogenous leukemia be cured?

It depends on the type. Some people with AML are cured by chemotherapy, with or without a stem cell transplant, particularly when the disease has favorable genetic features, but relapse is possible and follow-up continues for years. CML is often controlled very effectively with long-term medication, and although most people need to keep taking a TKI, a proportion with very deep responses can eventually stop treatment under supervision. Doctors tend to speak in terms of remission and long-term control rather than guaranteeing a cure.

How quickly does myelogenous leukemia treatment need to start?

AML is a medical emergency in many cases, and treatment often begins within days of diagnosis, sometimes while detailed genetic results are still being awaited. Chronic-phase CML is less urgent, and there is usually time to complete testing and discuss options over a week or two before starting a TKI. In either case, delays are kept to a minimum, and the team will explain the reasons for the timing.

What does a myelogenous leukemia diagnosis involve if my blood test was abnormal?

An abnormal blood count on its own does not confirm leukemia; infections, vitamin deficiencies, medications, and many other conditions can affect the numbers. If the doctor is concerned, the next steps usually include repeating the blood count, examining the blood under a microscope, and, if the findings remain suspicious, a bone marrow biopsy with genetic testing. Results from the marrow generally take several days to become available.

When to see a doctor

Many symptoms associated with myelogenous leukemia are common and usually harmless, but they deserve medical assessment when they persist, worsen, or occur together without an explanation. It is sensible to arrange a medical review for ongoing tiredness, repeated infections, unexplained bruising, or a fullness under the left ribs that lasts more than a couple of weeks. The following signs are considered urgent and need same-day medical attention, whether or not a diagnosis has already been made:

• Fever of 38 C (100.4 F) or higher, especially during or after chemotherapy, when the immune system may be weakened
• Bleeding that will not stop, heavy nosebleeds, blood in the urine or stool, or a sudden spread of tiny red or purple spots on the skin
• Severe shortness of breath, chest pain, or a racing heartbeat
• Sudden severe headache, confusion, drowsiness, weakness on one side of the body, or difficulty speaking
• Severe or rapidly worsening abdominal pain
• Signs of a serious infection such as shaking chills, a stiff neck, or rapid breathing
• Painful, swollen, or red skin around a central venous line

People already receiving treatment for myelogenous leukemia are usually given specific instructions about which symptoms to report and how quickly, and those instructions take priority over general guidance.