Primary CNS lymphoma

Shows one or more tumours, often deep in the brain.

A small needle biopsy confirms the diagnosis. Steroids are avoided before the biopsy where possible, as they can shrink the lymphoma and hide it under the microscope.

A slit-lamp examination by an eye doctor, as the lymphoma can involve the eyes.

Fluid from the lower back checks for lymphoma cells in the fluid around the brain.

PET-CT of the body (and testicular ultrasound in older men) to make sure the lymphoma has not started elsewhere. HIV test and kidney function before high-dose methotrexate.

Before starting chemotherapy, immunotherapy or targeted therapy, these tests check that you are fit for treatment, and give a starting point to compare with later.

Before immunotherapy, also:

Sometimes needed, depending on your treatment:

• Pregnancy test for women who could be pregnant.
• Calcium and magnesium: for example before cisplatin or bone-strengthening injections.
• Dental check-up before bone-strengthening injections (zoledronic acid or denosumab), as they can rarely affect the jaw bone.
• Hearing test before cisplatin, in some patients.
• Clotting tests (PT/INR) before a biopsy or chemoport.

Your doctor will choose the tests that apply to you. Some of them are repeated during treatment.

• The biopsy and staging tests confirm that this is primary CNS lymphoma, which is treated very differently from other brain tumours and from lymphoma elsewhere.
• Kidney function and fluid tests decide whether high-dose methotrexate can be given safely.

1. High-dose methotrexate-based chemotherapy, which reaches the brain. Often combined as MATRix: methotrexate, cytarabine, thiotepa and rituximab, every 3 weeks for 4 cycles.
2. Older or less fit patients: methotrexate with rituximab and a tablet such as temozolomide or procarbazine.

Side effects: methotrexate · chemotherapy

1. Fit patients: high-dose chemotherapy with stem cell transplant (own stem cells), to keep the lymphoma away.
2. Others: whole brain radiotherapy (lower dose), or maintenance tablets.

Side effects: chemotherapy · radiotherapy

1. Methotrexate again if the response lasted long, or other drugs such as ibrutinib or lenalidomide.
2. Transplant or radiotherapy in selected patients.

• Given in hospital over 2 to 3 days with plenty of IV fluids and soda bicarbonate to keep the urine alkaline.
• A rescue medicine (leucovorin) is given until the methotrexate level in the blood is low enough.
• Can affect the kidneys, liver and mouth. Some painkillers and antibiotics must be avoided; tell us about every medicine you take.

• Nausea and vomiting: well controlled with medicines given before and after chemotherapy.
• Low blood counts and infection risk: fever of 38°C or more needs urgent care.
• Tiredness, mouth sores, loose stools or constipation.
• Hair loss.
• After transplant: low counts for 2 to 3 weeks, and a higher infection risk for several months.

More about chemotherapy · Side effects of your regimen

• Tiredness and hair loss.
• Memory and concentration problems over years, especially in older patients.

Fever of 38°C or more after chemotherapy, passing much less urine during methotrexate, new confusion, weakness or seizures need urgent care.

When to seek help urgently