Intrathecal chemotherapy is a form of cancer treatment in which a healthcare professional injects chemotherapy drugs into the cerebrospinal fluid (CSF). This colorless fluid surrounds the brain and spinal cord, which form the central nervous system (CNS), to protect them from injuries. A doctor might recommend intrathecal chemotherapy if cancer affects the CNS.

A person can also receive chemotherapy in other forms, including oral, inhaled, and injectable. The type of chemotherapy that a doctor administers will depend on the type of cancer that a person has and which treatment can best meet their needs.

Keep reading to learn more about intrathecal chemotherapy, which cancers it can treat, how to prepare for the treatment, and what to expect during it.

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Doctors use chemotherapy treatment to kill cancer cells or stop them from spreading.

During intrathecal chemotherapy, a healthcare professional will administer the chemotherapy drugs into the fluid around the spinal cord during a lumbar puncture, or spinal tap. The person will usually receive a local anesthetic before the healthcare professional inserts a needle into the spinal area.

The American Cancer Society notes that healthcare professionals may also administer the chemotherapy drugs through a long-term catheter and port that sits under the skin on the head. The port is called an Ommaya reservoir.

The Ommaya reservoir has a small tube attached that enters the CSF through a cavity in the brain. A healthcare professional will remove the port once the person has completed their treatment.

Why is this form of chemotherapy necessary?

Macmillan Cancer Support, a British charity, explains that when cancer is in the CNS, chemotherapy treatments that a person receives in the form of pills or an intravenous (IV) infusion are unable to reach the CSF.

The reason for this is that a layer of protection called the blood-brain barrier surrounds the CNS. This barrier lets nutrients and oxygen enter the brain while preventing toxins and harmful substances from entering. The blood-brain barrier also effectively blocks IV or oral cancer medications from passing, which makes them far less effective.

A doctor may recommend intrathecal chemotherapy to achieve more targeted treatment straight to the CNS.

A person may need to undergo intrathecal chemotherapy to prevent cancer from reaching the CSF from other parts of the body and to target cancer cells in the area around the brain and the spinal cord.

According to the National Cancer Institute, intrathecal chemotherapy is a treatment option for cancers that have spread to the leptomeninges, which are membranes that cover the brain and spinal cord. When cancer spreads in this way, healthcare professionals refer to it as leptomeningeal carcinomatosis.

Cancer types that commonly spread to the leptomeninges include:

If a person has one of these types of cancer, a doctor may suggest intrathecal chemotherapy to prevent the cancer from spreading to the CSF and to treat cancerous cells that have reached the CNS.

Before a person’s intrathecal chemotherapy treatment, they should discuss the process with a doctor. The doctor will explain why they need the treatment, and the individual will need to give informed consent for the treatment if they wish to proceed with it.

A person should also speak with a doctor or cancer care team about:

  • the lumbar puncture
  • the chemotherapy treatment
  • what the treatment involves
  • any other available tests
  • the risks and side effects of intrathecal chemotherapy

People may find it helpful to have a friend or relative alongside them at the appointment to help them remember the relevant information. They may also wish to write down any questions they have before discussing the treatment with a doctor.

Once a doctor makes a diagnosis, they should explain the treatment plan to the person, including which medications they will use and how they will administer them.

A person may find it beneficial to go to the toilet before the treatment procedure because they will need to lie flat for a set period afterward.

Which medications will a healthcare professional administer?

The doctor will decide what dosage of intrathecal chemotherapy to administer depending on whether the aim of treatment is to destroy or prevent the cancer. They will also take into account various other factors, such as the person’s age, overall health, and weight.

Doctors may use different medications, either alone or in combination. These are likely to include methotrexate or cytarabine.

Doctors may also include corticosteroids to reduce or prevent inflammation of the arachnoid membrane, a protective membrane that covers the brain and spinal cord.

Procedures

A doctor can administer intrathecal chemotherapy in two different ways:

Lumbar puncture

This procedure involves a doctor inserting a needle into the spinal canal and injecting the medicine into the CSF between two vertebrae in the lower spine.

Before a person has a lumbar puncture, they will have lab tests to ensure that they have enough platelets for their blood to clot effectively afterward.

If their platelet levels are sufficient, the person will then lie on their side or sit with their head and chest resting on a surface to expose their spine. A doctor or nurse will administer a local anesthetic to numb the area. The individual may feel some pressure, but the procedure is not usually painful.

The treatment takes about 20 minutes. The person will need to remain still for 1 hour or more to allow the medication to move through the CSF.

Ommaya reservoir

A healthcare professional may recommend placing an Ommaya reservoir if a person requires multiple intrathecal chemotherapy treatments. This port will provide the healthcare team with safe, repeated access to the CSF.

An Ommaya reservoir is a small plastic device that a surgeon places under the scalp. It attaches to a catheter tube that allows the medication to reach an open area in the brain, where there is CSF.

When a doctor injects chemotherapy medication into the reservoir, it moves into the CSF without the doctor having to administer a lumbar puncture each time. It also allows the doctor to take samples of CSF from the person to monitor how the treatment is going.

There are some risks associated with an Ommaya reservoir, including:

  • infection
  • brain hemorrhage
  • brain bleeding

Although the treatment is not typically painful, a person may experience some side effects, including:

  • dizziness
  • back pain
  • headaches
  • weakness
  • nausea and vomiting
  • allergic reaction to the medication
  • fever

A person should speak with a doctor about what to expect from the treatment and how to manage any side effects. The doctor may recommend:

  • eating a healthy, nutrient-rich diet and staying hydrated
  • bringing a bag with comfort essentials, such as pillows, to chemotherapy appointments
  • taking time to rest and recover from the treatment
  • practicing good hygiene to minimize the chance of infection
  • asking friends and family members to help with everyday chores, such as shopping, cleaning, and cooking

The outlook for people with cancer that affects the CNS can vary. It will depend on the type of cancer that they have, as well as personal factors, such as their general health, age, and genetics.

Intrathecal chemotherapy is more effective than IV or oral chemotherapy for cancer that has spread to the CNS.

A doctor should be able to give a person more information about their specific outlook.

Learn more about survival and chemotherapy success rates for different cancers here.

A doctor may suggest intrathecal chemotherapy for people with cancer that affects the CNS. This treatment may be the best option because the blood-brain barrier can prevent oral or IV chemotherapy from being effective.

A healthcare professional will administer intrathecal chemotherapy by injecting it into the spinal canal during a lumbar puncture. They may also administer it through a plastic insert called an Ommaya reservoir, which sits under the scalp.

During treatment, the individual will receive a local anesthetic and lie down or sit forward to expose their spine for injection. The process is not usually painful, but it may take 20 minutes and require an hour or more of resting afterward.

Potential side effects include nausea, headaches, and dizziness. A person can help minimize these effects by eating a balanced diet, getting enough rest, asking for help with daily tasks, and practicing good hygiene.

The type and stage of cancer will affect a person’s outlook, as will their health history, age, genetics, and other underlying conditions.