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Why spinal chemotherapy is given in leukaemia | CION Cancer Clinics
Spinal chemotherapy is given because leukaemia cells, especially in ALL, can hide in the fluid around the brain and spinal cord, where drugs in the blood reach poorly. Putting chemotherapy directly into that fluid protects the brain from relapse, even when the first test is clear. This page explains how it is done, what a lumbar puncture feels like, what the report words mean and which signs need urgent care. At CION Cancer Clinics, every leukaemia, MDS and MPN case is reviewed by our haematologist and discussed at a tumour board before a plan is agreed.
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Medically reviewed by Dr. Basudev PokhrelConsultant Haematologist · last reviewed September 2026, next review due September 2027
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On this page
- Why is chemotherapy put into the spine in leukaemia?
- How is the brain and spine protected?
- What happens during a lumbar puncture?
- What do the spinal fluid report words mean?
- What do families worry about with spinal chemotherapy?
- What are the side effects, and what can this page not tell you?
- Common questions about spinal chemotherapy in leukaemia
The short answer
Why is chemotherapy put into the spine in leukaemia?
Spinal chemotherapy is given because leukaemia cells, especially in acute lymphoblastic leukaemia (ALL), can hide in the fluid around the brain and spinal cord. Most chemotherapy in the bloodstream cannot reach that fluid well, so the drug is put there directly to stop the leukaemia coming back in the brain.
What the brain's barrier has to do with it
The brain is protected by a tight lining of blood vessels, often called the blood-brain barrier. It keeps out germs and toxins. It also keeps out many medicines. Leukaemia cells that slip past it can sit in the spinal fluid, safe from treatment that is clearing the blood and bone marrow.
It is given even when no leukaemia is found there
This is the part that confuses families. The first spinal fluid test may be clear, and treatment is still given. That is the point of it. Before this kind of protection became routine, leukaemia often returned in the brain months after the blood looked clear. Treating the space in advance is far easier than treating a relapse there.
Who it applies to
Almost everyone treated for ALL, children and adults, receives it. It is also used in some other leukaemias and lymphomas that carry a higher risk of spreading to the brain. In most other blood cancers it is not needed, and your haematologist will say if it is part of your plan.
The options
How is the brain and spine protected?
Most plans use more than one of these. Which ones, and how often, depends on your protocol and on the first spinal fluid result.
Intrathecal chemotherapy
Chemotherapy injected into the spinal fluid through a thin needle in the lower back. It is repeated at intervals through every phase of treatment.
Drugs often used
- Methotrexate
- Cytarabine
- A steroid such as hydrocortisone
High-dose chemotherapy through a vein
Some drugs, given in large amounts through a drip, cross into the brain in useful amounts. This needs a hospital stay, fluids and blood tests to protect the kidneys.
Radiotherapy to the brain
Once widely used, it is now kept mainly for people whose leukaemia is already found in the spinal fluid, or for certain high-risk situations.
It can affect memory and hormones later, which is why it is used far less than before.Targeted tablets
In Philadelphia-positive ALL, some targeted tablets reach the brain better than others. This can influence which one is chosen.
Not sure whether this applies to you?
Ask an oncologistOn the day
What happens during a lumbar puncture?
Blood tests first
Platelets and clotting are checked. If platelets are low, a platelet transfusion may be given first to lower the chance of bleeding.
Positioning
You lie curled on your side or sit bent forward. This opens the gaps between the bones of the lower back. The skin is cleaned and numbed.
Fluid out, drug in
A thin needle goes in below the spinal cord. A little fluid is taken for testing, then the chemotherapy goes in. You may feel pressure, and sometimes a brief tingle down a leg.
Resting afterwards
Some centres ask you to lie down for a while. Drink fluids, and report a headache that is worse on sitting up.
On your report
What do the spinal fluid report words mean?
- CSF
- Cerebrospinal fluid. The clear fluid around the brain and spinal cord that is sampled during a lumbar puncture.
- CNS
- Central nervous system. The brain and spinal cord together.
- CNS 1
- No leukaemia cells were seen in the spinal fluid.
- CNS 2
- A few leukaemia cells were seen, but not enough to count as disease there. Extra intrathecal treatment is often added.
- CNS 3
- Leukaemia is present in the spinal fluid, or the brain or nerves are affected. Treatment to that area is stepped up.
- Traumatic tap
- Blood from the needle mixed into the sample. It can make the result harder to read.
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Signs that cannot wait
After a lumbar puncture or high-dose chemotherapy, go to the nearest emergency department the same day, or call 108, for a fit, confusion, slurred speech, sudden weakness on one side, severe headache with fever or a stiff neck, new numbness in the legs, or loss of bladder or bowel control. Say the person is on leukaemia treatment and has had spinal chemotherapy. Do not wait for the next visit.
Commonly believed
What do families worry about with spinal chemotherapy?
"Taking fluid from the spine can cause paralysis."
The needle goes in below the level where the spinal cord ends, into a space that holds only fluid and nerve roots. Serious nerve damage from a lumbar puncture is very rare.
"Treatment to the spine means the cancer has reached the brain."
In most people it has not. The treatment is given because it might go there, not because it already has.
"The first fluid test was clear, so we can skip the rest."
A clear result is good news, but a small number of hidden cells cannot be ruled out. Skipping planned doses removes the protection the protocol relies on.
"The headache afterwards means something went wrong."
A headache that eases on lying down is a known effect of fluid leaking from the needle hole. Tell the team. A headache with fever, stiff neck or confusion is different and needs emergency care.
Being straight with you
What are the side effects, and what can this page not tell you?
Most people manage repeated lumbar punctures with mild, short-lived effects. The common ones are back soreness at the needle site and a headache that is worse sitting up and better lying flat.
Less common effects
Methotrexate in the spinal fluid can occasionally cause a stroke-like episode, a fit or confusion, usually days after a dose. These often settle, but they need urgent assessment. Over the longer term, repeated treatment and especially brain radiotherapy can affect concentration and memory. Tell the team if you notice changes in thinking or school or work performance.
Who may need a different approach
People with very low platelets that do not rise with transfusion, an infection in the lower back skin, or raised pressure in the brain may need the procedure delayed or done differently. Some people have a small reservoir placed under the scalp instead.
What this page cannot tell you
It cannot tell you how many lumbar punctures your protocol includes, or whether radiotherapy will be needed. That depends on your leukaemia type, your first spinal fluid result and your risk group.
Questions we are asked
Common questions about spinal chemotherapy in leukaemia
Does a lumbar puncture hurt?
The numbing injection stings briefly. After that, most people feel pressure rather than sharp pain. Some feel a quick electric tingle down a leg if the needle brushes a nerve root, which passes at once. Tell the doctor if you are anxious. Some adults are offered sedation, depending on the centre.
How many times will it be done?
It is repeated many times across treatment, more often during the early phases and less often in maintenance. The exact number depends on your protocol and your first spinal fluid result. Ask the team for a written schedule so the family can plan travel around it.
Can we go home the same day?
Usually yes, when the lumbar puncture is the only treatment that day. You may be asked to rest for a while before leaving. If it is given with high-dose chemotherapy through a vein, a hospital stay is normally needed for fluids and blood tests.
What helps a headache after a lumbar puncture?
Lying flat, drinking fluids and resting usually help, and most headaches settle within a few days. Ask the team which pain relief is safe with your counts. If it lasts, the team can offer a simple procedure to seal the leak. Fever or a stiff neck with a headache needs emergency care.
Is this the same as a bone marrow test?
No. A bone marrow test takes a sample from the hip bone to check the leukaemia in the marrow. A lumbar puncture takes fluid from the spine and gives chemotherapy into it. Both may happen on the same day, but they are separate procedures with separate purposes.
Will spinal chemotherapy affect memory or studies?
Most adults notice no lasting change from intrathecal chemotherapy alone. Some describe slower thinking or poor concentration during treatment, often called chemo brain, which tends to improve. The risk of longer-term effects is higher with brain radiotherapy, which is now used far less often.
What if leukaemia is found in the spinal fluid?
The treatment to that area is increased. Intrathecal chemotherapy is given more often until the fluid is clear, and radiotherapy may be discussed. Finding it does not mean treatment will not work, but it does change the plan, and your haematologist will explain how.
Can we refuse or delay the lumbar punctures?
You have the right to ask questions and to take time to decide. Before refusing or delaying, talk openly with your haematologist about what worries you. Missing this treatment raises the chance of leukaemia returning in the brain, which is harder to treat. Often the worry can be addressed.
Your Haematologist
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Dr. Basudev Pokhrel reviews blood counts, transfusion needs and blood disorders, and works with the CION tumour board on blood cancers.
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Sources
- National Cancer Institute — Adult Acute Lymphoblastic Leukemia Treatment (PDQ), Patient Version
- Cancer Research UK — Acute lymphoblastic leukaemia (ALL)
- NHS — Lumbar puncture
- American Cancer Society — Acute Lymphocytic Leukemia (ALL)
This page is general information, not a prescription. Do not change or stop any treatment based on what you read here. If anything is worrying you, contact your own treating team — or call our helpline and we will help you reach the right specialist.
Keep reading
Related pages
Acute Lymphoblastic Leukaemia in AdultsThe overview of adult ALL, from diagnosis onwardsAdult ALL Treatment: The Phases ExplainedWhere spinal chemotherapy sits in each phasePhiladelphia-Positive ALL and TKI TreatmentHow targeted tablets fit alongside itBlood counts during chemotherapyWhy platelets are checked before every lumbar puncture
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