Leukemia

What is leukemia?

Bone marrow makes three kinds of blood cells: red cells that carry oxygen, white cells that fight infection, and platelets that help blood clot. All of them start as stem cells, which mature along two main lines: the lymphoid line (lymphocytes) and the myeloid line (most other white cells, red cells and platelets).

In leukemia, a genetic change in an early cell lets it multiply uncontrollably. The abnormal cells fill the marrow, so it cannot make enough normal cells, and they spill into the blood and sometimes the lymph nodes, spleen, liver, brain fluid or skin.

Types of leukemia

Less common types include hairy cell leukemia, acute promyelocytic leukemia (a subtype of AML that is a bleeding emergency but highly curable), chronic myelomonocytic leukemia and juvenile myelomonocytic leukemia.

Early signs and symptoms of leukemia

Most symptoms come from a shortage of normal blood cells.

From low red blood cells (anemia)

• tiredness and weakness that does not improve with rest
• pale skin
• shortness of breath on exertion, a fast heartbeat, dizziness

From low normal white blood cells

• infections that keep coming back or will not clear, such as chest infections, mouth sores or skin infections
• fevers without an obvious cause

From low platelets

• bruising easily or without injury
• tiny red or purple dots on the skin (petechiae)
• bleeding gums, nosebleeds, heavy periods, blood in urine

From leukemia cells building up

• bone or joint pain, especially in children
• swollen lymph nodes in the neck, armpit or groin
• fullness or pain under the left ribs from an enlarged spleen
• night sweats, unexplained weight loss, loss of appetite
• swollen, bleeding gums (especially in some AML types)
• headaches, vomiting or vision changes if the brain fluid is affected

Chronic leukemias often cause no symptoms at all and are discovered on a routine blood count.

Leukemia symptoms in children

Children with ALL often become pale, tired and irritable, get bruises in unusual places such as the back or chest, have fevers, and complain of bone or leg pain. Some limp or refuse to walk. Parents may notice swollen glands or a swollen belly. Most children with these symptoms have a common infection, but a blood count quickly tells the difference.

What causes leukemia?

In most people, no cause is found. Leukemia is not contagious and is not usually inherited. Known risk factors include:

• previous chemotherapy or radiation therapy
• high radiation exposure
• long-term exposure to benzene (in some industries and tobacco smoke)
• smoking, for AML
• genetic syndromes such as Down syndrome, Fanconi anemia and Li-Fraumeni syndrome
• blood disorders such as myelodysplastic syndrome
• a family history of CLL, which modestly raises risk
• age: most types become more common with age, except ALL

How leukemia is diagnosed

1. Complete blood count (CBC): shows high or low white cells, and often low red cells and platelets.
2. Blood smear: a specialist looks for immature "blast" cells or abnormal lymphocytes under the microscope.
3. Bone marrow aspiration and biopsy: a needle takes marrow from the back of the hip bone under local anesthetic. Acute leukemia is generally diagnosed when blasts make up at least 20% of marrow cells.
4. Flow cytometry: identifies the exact cell type from markers on the cell surface.
5. Genetic and molecular tests: look for chromosome changes and gene mutations, such as the Philadelphia chromosome (BCR-ABL1), FLT3, NPM1 and others. These guide treatment and predict outlook.
6. Lumbar puncture: checks for leukemia in the spinal fluid, especially in ALL.
7. Imaging: CT scans or ultrasound for lymph nodes and spleen when needed.

Leukemia treatment

Treatment depends on the type, genetic features, age and general health. It is planned by a hematologist-oncologist.

Acute leukemias

• Induction chemotherapy aims to clear leukemia from the marrow (remission), usually requiring weeks in the hospital.
• Consolidation and maintenance treatment kills remaining cells. In childhood ALL, total treatment lasts about 2 to 3 years, much of it as outpatient tablets.
• Targeted drugs such as FLT3 inhibitors, IDH inhibitors, tyrosine kinase inhibitors for Philadelphia-positive ALL, and venetoclax combinations for older adults with AML.
• Immunotherapy: antibodies such as blinatumomab and inotuzumab, and CAR T-cell therapy, in which a patient's own T cells are engineered to attack leukemia, for relapsed ALL.
• Stem cell (bone marrow) transplant for higher-risk or relapsed disease.

Chronic leukemias

• CML: daily tyrosine kinase inhibitor tablets such as imatinib keep most people in long-term remission. Some who achieve deep, stable responses can stop treatment under close monitoring.
• CLL: early, symptom-free CLL is monitored ("watch and wait"), because early treatment does not improve survival. When treatment is needed, targeted tablets such as BTK inhibitors or venetoclax, often with antibodies, have largely replaced traditional chemotherapy.

Supportive care

Blood and platelet transfusions, antibiotics and antifungals to prevent and treat infection, medicines to protect the kidneys (preventing tumor lysis syndrome), fertility preservation, and psychological support are all part of treatment.

Living with leukemia treatment

• Infection precautions: during low white cell counts (neutropenia), wash hands often, avoid sick contacts, and treat any fever as an emergency.
• Bleeding precautions: with low platelets, use a soft toothbrush and an electric razor, and avoid contact sports and NSAIDs such as aspirin and ibuprofen unless advised.
• Vaccines: inactivated vaccines such as flu and COVID-19 are usually recommended. Live vaccines are avoided during treatment.
• Late effects: survivors of childhood leukemia need long-term follow-up for heart, hormone, growth and learning effects.

Outlook and survival

Survival varies widely by type and age:

• Childhood ALL: about 90% of children are cured.
• Adult ALL: cure rates are lower, but newer immunotherapies have improved them.
• AML: about 1 in 3 adults overall survive 5 years, with much higher rates in younger adults and those with favorable genetics, and lower rates in older adults.
• CML: most people on targeted therapy have a life expectancy close to normal.
• CLL: many people live for many years, often more than 10, and some never need treatment.

These figures are averages. Your hematologist can give a more personal estimate based on your genetic results and response to treatment.

Frequently asked questions

What are the first signs of leukemia?

Early signs are usually tiredness, pale skin, frequent infections or fevers, and easy bruising or bleeding, such as nosebleeds, bleeding gums or tiny red spots on the skin. Bone pain and swollen glands are also common, especially in children. Chronic leukemia often has no early signs.

Is leukemia curable?

Many cases are. About 9 in 10 children with ALL are cured, and a stem cell transplant can cure some adults with acute leukemia. CML is usually controlled long term with tablets, and CLL is often managed for many years. Outcomes depend on type, genetics and age.

What is the difference between leukemia and lymphoma?

Both are cancers of white blood cells. Leukemia starts in the bone marrow and mainly affects the blood. Lymphoma starts in the lymph nodes and lymphatic tissue and usually appears as swollen glands or masses. Some conditions, such as CLL and small lymphocytic lymphoma, are the same disease seen in different places.

Can a blood test detect leukemia?

A complete blood count is usually the first clue, showing abnormal white cell numbers or low red cells and platelets. A blood smear can show leukemia cells. A bone marrow biopsy and genetic tests are needed to confirm the exact type and plan treatment.

What does leukemia bruising look like?

Leukemia bruises often appear without any injury, in unusual places such as the back, chest or belly, and may be larger than expected. They often come with petechiae, which are tiny flat red or purple dots that do not fade when pressed, usually on the legs.

Is leukemia hereditary?

Most leukemia is not inherited. It is caused by genetic changes that happen in marrow cells during life. A few inherited conditions raise the risk, and having a close relative with CLL increases risk slightly, but most relatives of people with leukemia never develop it.