Leukemia: Full guide

What is leukemia?

Leukemia is a cancer of the blood-forming cells. It starts in the bone marrow. Bone marrow is the soft, spongy tissue inside your bones where blood cells are made.

Your marrow normally makes three kinds of blood cells. White blood cells fight infection. Red blood cells carry oxygen. Platelets help your blood clot. In leukemia, abnormal white blood cells grow out of control. They crowd out the healthy cells.

Doctors sort leukemia in two ways. The first is how fast it grows. Acute leukemia grows fast and needs treatment right away. Chronic leukemia grows slowly, sometimes over many years.

The second is which kind of cell it starts in. Myeloid leukemia starts in cells that would become red cells, platelets, or certain white cells. Lymphoid (or lymphocytic) leukemia starts in lymphocytes, the white cells that make up much of your immune system.

Putting these together gives four main types: AML, ALL, CML, and CLL. Each type is treated very differently. Knowing your exact type, and the gene changes in your leukemia cells, is the most important first step.

Some people feel tired, get infections often, or bruise and bleed easily. Others have no symptoms, and the leukemia is found on a routine blood test. Your care team will explain the goal of your treatment.

Types

Acute myeloid leukemia (AML)

A fast-growing leukemia of myeloid cells. It is the most common acute leukemia in adults and is more common in older people. It needs treatment soon after diagnosis.

Acute promyelocytic leukemia (APL)

A special type of AML. It can cause serious bleeding at first, so it is treated as an emergency. With modern treatment, most people with APL are cured.

Acute lymphoblastic leukemia (ALL)

A fast-growing leukemia of young lymphocytes called lymphoblasts. It is the most common cancer in children, but adults get it too. Most adult ALL starts in B cells. Some starts in T cells.

Philadelphia chromosome-positive ALL (Ph+ ALL)

A type of ALL with a gene change called BCR-ABL. It is more common in older adults. Targeted pills called TKIs have greatly improved results for this type.

Chronic myeloid leukemia (CML)

A slow-growing leukemia of myeloid cells caused by the BCR-ABL gene change. Most people are found in the early, chronic phase. With daily pills, many people live close to a normal life span.

Chronic lymphocytic leukemia (CLL)

A slow-growing leukemia of B cells. It is the most common leukemia in adults in the US. Many people do not need treatment for years.

Small lymphocytic lymphoma (SLL)

The same disease as CLL, but the cells are mostly in the lymph nodes instead of the blood. It is treated the same way as CLL.

Other types

These include rare types like hairy cell leukemia. Mixed-phenotype leukemia has features of both myeloid and lymphoid cells. Ask your care team which type you have.

Tests you may have

Complete blood count (CBC)

A blood test that counts your white cells, red cells, and platelets. It is often the first sign of leukemia. You will have it many times during treatment.

Blood smear

A drop of blood is looked at under a microscope. The doctor looks for young leukemia cells called blasts, or other unusual cells.

Bone marrow biopsy and aspirate

A needle takes a small sample of marrow and bone, usually from the back of the hip. You get numbing medicine first, and some people get medicine to relax. It confirms the diagnosis and is repeated to see if treatment is working.

Flow cytometry

A lab test that reads markers on the surface of cells. It tells whether the leukemia is myeloid or lymphoid, B cell or T cell. It can also find very small amounts of leukemia left after treatment.

Chromosome and gene tests

Tests called cytogenetics, FISH, and next-generation sequencing look for changes in the leukemia cells' chromosomes and genes. The results help predict how the leukemia will behave and which drugs may work best.

Lumbar puncture (spinal tap)

A thin needle takes fluid from the lower back. It checks if leukemia is in the brain or spinal cord. It is routine in ALL, and chemotherapy can be given into the fluid at the same time.

Heart test (echocardiogram)

An ultrasound of the heart. It is done before some chemotherapy drugs, like daunorubicin, that can affect the heart.

HLA typing

A blood or cheek swab test that shows your tissue type. It is used to find a matching donor if a stem cell transplant may be needed. Brothers and sisters may be tested too.

Other blood tests

These check your kidneys, liver, clotting, and signs of infection such as hepatitis B or HIV. They also check for tumor lysis syndrome, which can happen when many leukemia cells die at once.

Risk groups and phases

Most leukemias do not have stages like other cancers. That is because leukemia is already in the blood and marrow throughout the body. Instead, doctors use risk groups or phases.

Risk groups are mostly based on gene and chromosome changes in the leukemia cells. They help predict how well the leukemia will respond. They also help decide whether a stem cell transplant is a good idea.

AML risk groups

AML is sorted into favorable, intermediate, or adverse (higher) risk based on gene tests. People in the adverse group are more often offered a stem cell transplant in first remission.

ALL risk groups

Some gene changes are linked to better results, and others to a higher chance of the leukemia coming back. Age and how quickly the leukemia clears with treatment also matter.

Measurable residual disease (MRD)

Very sensitive tests look for tiny amounts of leukemia after treatment. Being MRD-negative, meaning none is found, is a good sign. MRD results often guide the next steps, especially in ALL.

CML phases

CML has phases instead of stages. Most people are found in the chronic phase, when the disease is stable. The accelerated and blast phases are more advanced and act more like acute leukemia.

CML risk scores

Scores such as Sokal and ELTS use your age, spleen size, and blood counts. They help your doctor choose which TKI pill to start with.

CLL stages

CLL does use stages, called Rai or Binet. They are based on blood counts and whether lymph nodes, spleen, or liver are enlarged. A higher stage does not always mean you need treatment now.

CLL-IPI score

A score that combines age, stage, a blood protein, and gene test results. It helps predict how CLL may behave over time.

Remission

Complete remission means no signs of leukemia on blood and marrow tests, and blood counts have recovered. It does not always mean cure, so more treatment is often given to keep it away.

Genetic and molecular tests

Leukemia cells have changes in their genes that healthy cells do not. Testing for these changes is a key part of diagnosis. Some results point to a targeted drug made for that exact change.

Results can take days to a couple of weeks. In AML, your team may wait for some results before choosing a plan, if it is safe. It helps to ask what your results mean for your treatment.

FLT3

A gene that is changed in about a third of people with AML. It can make AML grow faster. Pills called FLT3 inhibitors, such as midostaurin, quizartinib, or gilteritinib, target this change.

NPM1

One of the most common gene changes in AML. When found without other high-risk changes, it often means a better outlook. It can also be used to track tiny amounts of leukemia after treatment.

IDH1 and IDH2

Gene changes found in some people with AML. Pills such as ivosidenib (IDH1) and enasidenib (IDH2) target them.

TP53

A gene that normally helps stop cancer growth. When it is changed, leukemia is harder to treat. In CLL, a TP53 change or a missing piece of chromosome 17 (del 17p) matters. Chemotherapy does not work well then, so targeted drugs are used.

BCR-ABL (Philadelphia chromosome)

Two genes that break and join together to make a new gene. It causes CML and some ALL. TKI pills block it. A blood test for BCR-ABL levels shows how well treatment is working.

IGHV mutation status

A test in CLL. "Mutated" IGHV usually means a slower-growing CLL. "Unmutated" IGHV means it may grow faster. It helps guide the choice of treatment.

PML-RARA

The gene change that causes acute promyelocytic leukemia (APL). Finding it means treatment with ATRA and arsenic trioxide, which work very well.

KMT2A

A gene change seen in some AML and ALL. Newer pills called menin inhibitors can be an option if the leukemia comes back.

CD19, CD22, and CD33

Markers on the surface of leukemia cells. Some drugs are aimed at them. Blinatumomab and CAR T cells target CD19 in B-cell ALL. Inotuzumab targets CD22. Gemtuzumab targets CD33 in AML.

Main treatments

Induction chemotherapy

The first, strong round of chemotherapy for acute leukemia. The goal is remission. For AML, a common plan is "7+3" (cytarabine and daunorubicin). You usually stay in the hospital for several weeks while your counts recover.

Consolidation and maintenance

More treatment after remission to kill leukemia cells that tests cannot see. In ALL, maintenance with pills and some IV drugs often lasts two to three years. Some people with AML take oral azacitidine to help keep remission.

Venetoclax combinations

Venetoclax is a pill that helps leukemia cells die. For AML, it is given with azacitidine or decitabine to people who are older or cannot have strong chemotherapy. For CLL, it is given for a set time with obinutuzumab or with a BTK inhibitor.

Targeted pills for AML

FLT3 inhibitors are added to chemotherapy if the leukemia has a FLT3 change. IDH inhibitors and menin inhibitors can be used for certain gene changes. For APL, ATRA and arsenic trioxide are the main treatment.

TKIs for CML

Tyrosine kinase inhibitors (TKIs) are daily pills that block BCR-ABL. Examples are imatinib, dasatinib, nilotinib, bosutinib, asciminib, and ponatinib. Your doctor picks one based on your risk score, other health problems, and side effects. TKIs are also used in Ph+ ALL.

BTK inhibitors for CLL

Daily pills that block a signal CLL cells need to grow. Examples are acalabrutinib, zanubrutinib, and ibrutinib. They are often taken for as long as they keep working. Pirtobrutinib can be used after other BTK inhibitors.

Blinatumomab and inotuzumab for ALL

Blinatumomab links your T cells to B-cell ALL cells so they can be killed. It is given as a continuous IV drip through a small pump. It is now part of first treatment for many adults. Inotuzumab carries a strong drug straight to ALL cells.

CAR T-cell therapy

Your own T cells are collected and changed in a lab to find and kill leukemia cells. They are given back through a vein. It is used for B-cell ALL that comes back or does not respond, and for some CLL.

Stem cell transplant

High-dose treatment followed by healthy blood-forming cells from a donor (an allogeneic transplant). The donor's immune system can also attack the leukemia. It may be offered for higher-risk AML or ALL, or when leukemia comes back.

Watch and wait, and clinical trials

Many people with CLL do not need treatment until the disease causes problems. Starting early does not help them live longer. Clinical trials test new treatments and can be a good option at any point.

Infection, transfusion, and other side effects

Infections

Leukemia and its treatment lower the white cells that fight germs. A fever can be an emergency. Wash hands often, avoid sick people, and ask before eating raw or undercooked foods. You may take pills to prevent bacterial, fungal, or viral infections.

Blood and platelet transfusions

Many people need red blood cell transfusions for anemia (low red cells) and platelet transfusions to prevent bleeding. Blood products are specially treated to be safe for people with weak immune systems. Ask your team what counts are checked and when you need a transfusion.

Bleeding and bruising

Low platelets can cause easy bruising, nosebleeds, or bleeding gums. Use a soft toothbrush and an electric razor. Avoid aspirin and ibuprofen unless your team says they are safe.

Fatigue

Feeling very tired is common, often from low red cells. Light activity like short walks can help. Rest when needed, and let others help with chores.

Tumor lysis syndrome

When many leukemia cells die fast, they release salts and acids that can harm the kidneys. You may get extra fluids and medicine to prevent it, and frequent blood tests at the start of treatment.

Nausea and mouth sores

Take anti-nausea medicine as prescribed, even before you feel sick. Eat small meals often. Rinse your mouth often and ask about special mouthwashes for sores.

Differentiation syndrome

Some AML and APL drugs make leukemia cells grow up quickly. This can cause fever, trouble breathing, swelling, or fast weight gain. It is treatable with steroids if caught early, so call right away.

Pill side effects (TKIs and BTK inhibitors)

These can include swelling, diarrhea, muscle cramps, rash, bruising, high blood pressure, or an irregular heartbeat. Take them exactly as prescribed. Check with your team or pharmacist before starting any new medicine, supplement, or grapefruit.

CRS and ICANS

After CAR T cells or blinatumomab, a strong immune reaction (CRS) can cause fever and low blood pressure. Some people get confused or have trouble speaking (ICANS). Caregivers should watch for these and call right away.

Graft-versus-host disease (GVHD)

After a donor transplant, donor immune cells can attack your body. It can cause rash, diarrhea, or liver problems. You will take medicines to prevent it and be watched closely.

Living with and after leukemia

After treatment for acute leukemia, you will have regular blood tests and sometimes bone marrow tests. These check that the leukemia has not come back. Tell your care team about fevers, new bruises, or feeling more tired.

With CML, many people take a daily pill for years and live a normal life. Taking every dose matters. Some people with a very deep, lasting response may be able to stop their pill under close watch. This is called treatment-free remission. Never stop on your own.

With CLL, living with leukemia is often like living with a long-term condition. You may have long times with no treatment. People with CLL have a higher risk of infections and skin cancers. Stay up to date on vaccines and get regular skin checks.

Treatment can affect fertility. If you may want children, ask about saving sperm or eggs before treatment starts, if time allows. Some treatments and transplant can also affect your heart, bones, or hormones years later. Ask what checkups you need.

After a stem cell transplant, you will need to get your childhood vaccines again. Recovery can take months to a year or more.

It is normal to feel worried, sad, or overwhelmed. Caregivers often carry a heavy load too. Social workers, counselors, and support groups can help you and your family.