• International Prognostic Index (IPI): A five-point score (age, stage, performance status, LDH, extranodal sites) that predicts how risky a lymphoma is before treatment.
• Prognostic Index for T-cell lymphoma (PIT): A four-item score that estimates the outlook in nodal T-cell lymphoma, built because the index used for B-cell lymphoma separated these patients poorly.
• B-cell, T-cell and NK-cell lymphoma: The first thing a lymphoma report says is which kind of lymphocyte the cancer came from.
• 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.
• 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.
• The lymphoma regimen alphabet: R-CHOP, pola-R-CHP, DA-EPOCH-R, ABVD, BEACOPP and the rest: Lymphoma treatment is written in acronyms, one letter per drug.

Making the diagnosis: CD30 and ALK immunohistochemistry on the biopsy. The diagnosis is partly a negative one: uniform strong CD30 with an anaplastic appearance and no ALK, in a lymphoma that is not confined to the skin and is not associated with a breast implant. Those two exclusions matter because both of them are treated very differently. Testing for DUSP22 and TP63 rearrangements is done where it is available, with the caution that WHO-HAEM5 does not regard the resulting groups as established subtypes.

Biomarker results to ask for: Uniform strong CD30 on every tumour cell, Absence of ALK protein by immunohistochemistry, which is the defining negative, DUSP22 rearrangement, whose prognostic meaning is disputed; WHO-HAEM5 records that the favourable association first reported has not been confirmed, TP63 rearrangement, loss of TP53 and overexpression of the interleukin-2 receptor alpha chain, each associated with worse outcomes, The Prognostic Index for T-cell lymphoma and the International Prognostic Index.

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: Brentuximab vedotin with cyclophosphamide, doxorubicin and prednisone, the same regimen as for ALK-positive disease and on the same trial: in ECHELON-2, five-year progression-free survival was 51.4 per cent against 43.0 with chemotherapy alone and overall survival 70.1 against 61.0. Consolidating a first remission with high-dose therapy and an autologous stem cell transplant is standard practice here, unlike in ALK-positive disease, and it rests on a single-arm study and registry comparisons rather than on a randomised trial; a patient is entitled to be told that. The regimens are on the peripheral T-cell lymphoma page. (ECHELON-2, Brentuximab vedotin, Cyclophosphamide, Doxorubicin, Prednisone, Autologous stem cell transplant (high-dose therapy), Stem cell transplant in lymphoma: what it is still for, Peripheral T-cell lymphomas (including cutaneous T-cell lymphoma))

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