• International Prognostic Index (IPI): A five-point score (age, stage, performance status, LDH, extranodal sites) that predicts how risky a lymphoma is before treatment.
• CNS prophylaxis in aggressive B-cell lymphoma, and the evidence against it: Some people with aggressive lymphoma are given extra methotrexate, into the spine or into a vein, to stop the lymphoma reaching the brain.
• MYD88 L265P and CXCR4 mutations: One letter change in MYD88 (L265P) keeps a B-cell survival signal permanently on; it is found in more than nine in ten Waldenström's macroglobulinaemia, most primary CNS and testicular lymphomas and a poor-risk group of DLBCL, and it predicts that BTK inhibitors will work, while a second mutation in CXCR4 predicts that they will work more slowly.
• Intrathecal therapy (lumbar puncture, Ommaya reservoir): Giving drugs directly into the fluid around the brain and spinal cord, by needle in the lower back or through a small reservoir under the scalp, because most drugs cannot cross from the blood into that space.
• Fertility before lymphoma treatment: what to ask for, and when: Several lymphoma treatments can end fertility, and the chance to preserve it exists only before the first dose.
• Stem cell transplant in lymphoma: what it is still for: An autologous transplant is very high-dose chemotherapy followed by the patient's own stored stem cells to rescue the bone marrow.
• Lugano classification / Ann Arbor staging: The Lugano classification is the lymphoma staging system: stage I to IV by how many lymph node regions and organs are involved, with PET-based response criteria.
• Nodal and extranodal lymphoma: A lymphoma that starts in a lymph node is called nodal; one that starts in an organ is called extranodal.
• The two lymphoma classifications of 2022 (WHO-HAEM5 and ICC): Since 2022 there have been two reference classifications of lymphoma rather than one, published within months of each other by overlapping groups of experts.

Diagnosis and staging: A solid testicular mass is removed through the groin rather than biopsied, so the diagnosis is usually made on the removed testicle. Staging then has to cover the sites this disease travels to: computed tomography or PET-CT of the body, imaging of the brain, examination of the spinal fluid, and examination of the remaining testicle. Sperm banking is discussed before treatment where it is relevant, because radiotherapy to the remaining testicle causes infertility and low testosterone.

Biomarker results to ask for: An activated B-cell (non-germinal-centre) phenotype: CD10 negative, MUM1 positive, BCL6 positive, Concurrent MYD88 and CD79B mutations, the genetic signature shared with lymphoma of the brain and of the eye, Loss of MHC class I and II and of beta-2-microglobulin, which is how the tumour escapes immune recognition, Epstein-Barr virus, which is characteristically negative, Imaging of the brain and examination of the spinal fluid at diagnosis, because the central nervous system is where this disease relapses.

Scans and tests linked to this cancer: FDG PET, Histopathology & immunohistochemistry.

Bring copies of scan reports, pathology and blood results, and a list of every medicine and supplement.

• First-line treatment of stage I and II disease: Rituximab with cyclophosphamide, doxorubicin, vincristine and prednisone for six to eight cycles, methotrexate into the spinal fluid, and radiotherapy to the remaining testicle. In IELSG-10, which treated 53 men this way, five-year progression-free survival was 74 per cent and overall survival 85 per cent at a median follow-up of 65 months; the five-year cumulative incidence of relapse in the central nervous system was 6 per cent and there were no relapses in the irradiated testicle. Grade 3 or 4 neutropenia occurred in 28 per cent and infection in 4 per cent. (Rituximab, Cyclophosphamide, Doxorubicin, Vincristine, Prednisone, Methotrexate, Intrathecal therapy (lumbar puncture, Ommaya reservoir), IMRT / IGRT (modern external beam), CNS prophylaxis in aggressive B-cell lymphoma, and the evidence against it)
• What happens at relapse: Relapse is most often in the central nervous system, and it is treated on the pathway for lymphoma of the brain rather than on the pathway for nodal lymphoma: regimens built around high-dose methotrexate that crosses into the brain, and consideration of high-dose therapy with an autologous stem cell transplant using a conditioning regimen that also reaches the brain. The detail is on the primary central nervous system lymphoma page. (Primary CNS lymphoma, Methotrexate, Autologous stem cell transplant (high-dose therapy), Stem cell transplant in lymphoma: what it is still for)

From the standard of care recorded for this cancer; which apply depends on your stage and biomarkers. Ask which the team recommends and why.