What is acute lymphoblastic leukemia (ALL)?

Acute lymphoblastic leukemia (ALL) is a cancer of young white blood cells called lymphoblasts. It starts in the bone marrow. Bone marrow is the soft, spongy tissue inside your bones where blood cells are made. Lymphoblasts normally grow into lymphocytes, the white cells that help your immune system fight infection. In ALL, these young cells grow out of control and do not mature. They crowd out healthy red cells, white cells, and platelets. ALL can also spread to the brain and spinal fluid, lymph nodes, spleen, or liver.

When should I call my care team?

Fever of 100.4 F (38 C) or higher, or shaking chills, even if you feel okay otherwise; Bleeding that will not stop, blood in your urine or stool, black stools, or vomiting blood; Severe belly pain that may spread to your back, with or without vomiting (possible pancreatitis from asparaginase); Swelling, pain, or warmth in one leg or arm, sudden shortness of breath, or chest pain (possible blood clot); Sudden severe headache, confusion, a seizure, vision changes, or weakness on one side; During blinatumomab or after CAR T: fever, dizziness, confusion, shaking, trouble speaking or writing, or unusual sleepiness; A problem with your blinatumomab pump, such as an alarm, a leak, or the line coming loose; Belly swelling, fast weight gain, or yellow skin or eyes (possible liver problem); Not being able to keep fluids or your pills down, or passing much less urine than usual; After a donor transplant: a new rash, diarrhea, or yellow skin or eyes.

Acute lymphoblastic leukemia (ALL)

ALL in adults is a fast-growing blood cancer, and newer targeted pills and immune treatments have greatly improved the chance of cure.

Hi, I'm Rosa. Today we'll go through acute lymphoblastic leukemia in adults, together, one step at a time. I'll keep it simple, and you can pause me, go back, or skip ahead whenever you like. Just so you know, this is for learning only. It is not medical advice, so please check everything with your own doctor and care team. Okay, let's get started.

What this leukemia is

Let's start with the basics. Acute lymphoblastic leukemia is a blood cancer. It starts in the bone marrow. That is the soft, spongy inside of your bones, where blood cells are made. In this leukemia, young white cells grow out of control. They do not grow up into healthy cells. They crowd out the good cells. So you may feel tired, get infections, or bruise easily. It grows fast, so treatment starts soon. It can also reach the fluid around the brain. Many adults are cured. Your care team will explain the goal for you.

The main types

Let's talk briefly about the types. Most adults have the B-cell type. Some have the T-cell type. That one often causes a lump in the chest. The biggest question is about something called the Philadelphia chromosome. It is a swap between two chromosomes. About one in four adults has it. If you have it, you will take a daily targeted pill. That pill has changed the outlook a lot. There is also a type that acts like it, without the swap. Your care team will tell you which type you have.

Tests you may have

Now let's talk about tests. A blood count is often the first clue. A bone marrow biopsy confirms the diagnosis. A needle takes a small sample from the back of your hip. You get numbing medicine first. Lab tests show if it is the B-cell or T-cell type. Gene tests look for the Philadelphia chromosome and other changes. A spinal tap checks the fluid around your brain and spine. Medicine is often given into that fluid at the same time. You will have very sensitive tests during treatment to look for tiny amounts of leukemia.

Risk and phases

Next up, risk and phases. This leukemia does not have stages like many other cancers. Instead, doctors look at risk. That depends on your age, your white blood count, and gene changes. The most important sign is how well treatment works in the first months. Very sensitive tests check for tiny amounts of leukemia left behind. Treatment is long, often two to three years. First comes induction, to reach remission. Then comes a few months of stronger treatment. Last comes about two years of gentler pills, called maintenance.

Gene and lab tests

Before we move to treatment, there are some things to know. Leukemia cells have gene changes and markers on their surface. The Philadelphia chromosome is the most important one in adults. It means you will take a targeted pill. Markers on the outside of the cells show which immune treatments can work. Another key test looks for tiny amounts of leukemia left after treatment. A good result is a very good sign. If some leukemia is still found, your team may add treatment. Your doctor will tell you what your results mean. The Questions to ask page can help you prepare.

Main treatments

Now let's talk about treatment. Most people get many chemotherapy drugs over two to three years. Young adults often do best with plans like those used for children. Everyone gets medicine into the spinal fluid, to protect the brain. Newer immune drugs help your own immune cells find the leukemia. One is given through a small pump you carry. If you have the Philadelphia chromosome, you take a daily targeted pill. Some people need a stem cell transplant from a donor. If the leukemia comes back, a cell therapy using your own immune cells may help. Ask your team about clinical trials too.

Side effects and help

Let's look at side effects. Infections are more likely when your counts are low. A fever is an emergency, so call right away. Many people need blood and platelet transfusions. One key drug can cause severe belly pain or blood clots. Call right away if that happens. Steroids can raise blood sugar and affect mood and sleep. Over time they can hurt the hip or knee joints. Another drug can cause tingling in the hands and feet, and constipation. The immune treatments can cause fever or confusion. You will be watched closely. We have a whole side effects guide on this site.

Living with and after it

Now let's talk about life during and after treatment. The first months are the hardest. Later, during maintenance, many people go back to work or school. Taking every pill matters. After treatment, you will have regular blood tests. Some effects can show up years later, in the bones, heart, or nerves. Ask about a plan for long-term checkups. Feelings matter too. Support groups and counselors can help you and your family. Call your care team right away for a fever, bleeding, or severe belly pain. If it feels very bad, call 911. Also visit our Screening, prevention and survivorship section.

You did great today. That was a lot, and you took it one step at a time. Write down your questions and bring them to your next visit. Call your care team any time something worries you, day or night. Treatment is a long road, and you do not have to walk it alone.

Call your care team right away if you have

Fever of 100.4 F (38 C) or higher, or shaking chills, even if you feel okay otherwise
Bleeding that will not stop, blood in your urine or stool, black stools, or vomiting blood
Severe belly pain that may spread to your back, with or without vomiting (possible pancreatitis from asparaginase)
Swelling, pain, or warmth in one leg or arm, sudden shortness of breath, or chest pain (possible blood clot)
Sudden severe headache, confusion, a seizure, vision changes, or weakness on one side
During blinatumomab or after CAR T: fever, dizziness, confusion, shaking, trouble speaking or writing, or unusual sleepiness
A problem with your blinatumomab pump, such as an alarm, a leak, or the line coming loose
Belly swelling, fast weight gain, or yellow skin or eyes (possible liver problem)
Not being able to keep fluids or your pills down, or passing much less urine than usual
After a donor transplant: a new rash, diarrhea, or yellow skin or eyes

Side effects: what helps

Sources

Quick answers

What is acute lymphoblastic leukemia (ALL)?: Acute lymphoblastic leukemia (ALL) is a cancer of young white blood cells called lymphoblasts. It starts in the bone marrow. Bone marrow is the soft, spongy tissue inside your bones where blood cells are made. Lymphoblasts normally grow into lymphocytes, the white cells that help your immune system fight infection. In ALL, these young cells grow out of control and do not mature. They crowd out healthy red cells, white cells, and platelets. ALL can also spread to the brain and spinal fluid, lymph nodes, spleen, or liver.
When should I call my care team?: Fever of 100.4 F (38 C) or higher, or shaking chills, even if you feel okay otherwise; Bleeding that will not stop, blood in your urine or stool, black stools, or vomiting blood; Severe belly pain that may spread to your back, with or without vomiting (possible pancreatitis from asparaginase); Swelling, pain, or warmth in one leg or arm, sudden shortness of breath, or chest pain (possible blood clot); Sudden severe headache, confusion, a seizure, vision changes, or weakness on one side; During blinatumomab or after CAR T: fever, dizziness, confusion, shaking, trouble speaking or writing, or unusual sleepiness; A problem with your blinatumomab pump, such as an alarm, a leak, or the line coming loose; Belly swelling, fast weight gain, or yellow skin or eyes (possible liver problem); Not being able to keep fluids or your pills down, or passing much less urine than usual; After a donor transplant: a new rash, diarrhea, or yellow skin or eyes.

Last updated: 2026-10-27. Medically reviewed by Veli Bakalov, MD, medical oncologist (October 2026). General education from Step by Step, the patient portal of HemeOncBuddy.