What Is Intrathecal Chemotherapy?

Medically Reviewed by Sabrina Felson, MD on November 14, 2022
3 min read

Sometimes cancer cells are able to cross into the fluid that surrounds and protects your brain and spinal cord. Cancer drugs you take by mouth or through a vein can’t get through as easily. Intrathecal chemo is a way to deliver the medicine you need in a direct way.

Your brain and spinal cord are protected by three layers of tissue called meninges. Between two of the layers is your cerebrospinal fluid, or CSF, in a place called the intrathecal space. That’s why cancer-fighting drugs placed into this space are called intrathecal chemotherapy, or IT chemo.

Intrathecal chemo is used most often to treat cancers that involve the brain or spinal cord or have a high risk of spreading there.  For example, some forms of leukemia and lymphoma are more likely than others to spread to the CSF over time. This could happen for up to half of people with acute lymphoblastic leukemia (ALL). If you have ALL, you may get IT chemo before cancer cells reach your CSF. It might also be a treatment for you if you have Burkitt lymphoma, lymphoblastic lymphoma, or diffuse large B-cell lymphoma.

You might have IT chemo as a treatment if your doctors find cancer cells already in the CSF. There’s about a 5% chance that cells from breast cancer, lung cancer, and melanoma, among others, will spread to the CFS or to the meninges over time.

One way to get this treatment is with a lumbar puncture, or spinal tap. This is the same method used to get a sample of your fluid to test for cancer cells. Your doctor will use a needle and syringe to deliver the medicine into your CSF between two vertebrae in your spine. You’ll lie on your side and get a numbing agent to lessen discomfort before the actual injection. The process takes about 30 minutes. Afterward, you’ll stay still for at least an hour to let the drug move through the intrathecal space.

If you need many doses or will get your medicines over a long period, your doctor may suggest an implant so you don’t need as many spinal taps. This is a small dome-shaped device called an Ommaya reservoir. It’s placed under your scalp during a short surgery. It has a catheter that connects to the intrathecal space.

Getting chemo this way is like getting it through an IV port elsewhere in the body. Also, if you need future CSF tests, doctors can take fluid through the device. This means less discomfort, but as with other types of surgery, there is a small risk of infection.

Methotrexate and cytarabine are the most common anti-cancer drugs given by IT chemo, both to prevent and to treat it. Each drug can be used alone or together. They’re often mixed with a steroid like prednisone or dexamethasone. For prevention, your dose will depend on your unique situation. For treatment, in general, you’ll likely get two doses a week at first and then one weekly or monthly.

The biologic rituximab, sometimes in combination with methotrexate, is used for some types of lymphoma. If you have HER2+ breast cancer, your IT chemo might include trastuzumab, a biologic that targets breast cancer in particular.


About 30% of people will have some side effects after IT chemo. Some are from the medicine, others from the method. The most common one is a headache. With a spinal tap, you might get a cluster of side effects called post-lumbar puncture headache, or PLPH. Other symptoms are back pain, nausea, vomiting, and fever. You might feel worse after you stand up and get better after you lie down. Rest and pain relievers should help. You may need at least 6 and as much as 10 hours of bed rest after a treatment.

More serious side effects are

  • Confusion
  • Drowsiness
  • A lack of coordination
  • Difficulty walking (ataxia) or talking (aphasia)

Rare complications include

  • Seizures
  • Paralysis in your lower body
  • Palsy (weakness, numbness, and shaking in your muscles)

Let your doctor know if you have any serious side effects, or you get new or worse ones, especially if you have blurry vision, dizziness or bleeding or nausea/vomiting that won’t stop.