• Watch and wait in lymphoma: when the right treatment is none yet: For slow-growing lymphomas that are not causing symptoms, treating straight away does not help people live longer.
• Indolent and aggressive lymphoma: Lymphomas are split by how fast they grow, and the split decides what happens next.
• 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.
• Radiotherapy in lymphoma: involved-site fields, 24 Gy, 4 Gy and total skin electron therapy: Lymphoma is one of the most radiation-sensitive cancers there is, so the doses are low and the fields are small.

Diagnosis and staging: A biopsy of the lesion is needed, because about a third of lymphomas at this site are not marginal zone lymphomas and the treatment differs. Imaging of the orbit, usually by magnetic resonance, maps the extent and the relationship to the optic nerve and the muscles. Staging of the rest of the body follows, because apparently localised ocular disease is sometimes part of a systemic marginal zone lymphoma. Both orbits are examined; bilateral disease is common and does not by itself mean the lymphoma has spread.

Biomarker results to ask for: A marginal zone phenotype: CD20 positive, CD5 negative, CD10 negative, often with plasmacytic differentiation, TNFAIP3 mutation or deletion, commoner here than at other marginal zone sites, Gain of chromosome 6p and loss of 6q, recurrent in ocular adnexal disease and not at other extranodal sites, Chlamydia psittaci, found in Italian series and absent from several United States series; the association varies by region, Staging of the orbit by magnetic resonance imaging, and of the rest of the body to exclude disease elsewhere.

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.

• Localised disease: radiotherapy, and an antibiotic where the evidence supports it: Radiotherapy to the orbit is the standard treatment for disease confined to the ocular adnexa and it controls it in almost everybody. In a series of 28 patients irradiated after a trial of doxycycline, 30 to 36 Gy in 15 to 18 fractions produced a response in all of them and a complete response in 89 per cent, with four-year progression-free survival of 74 per cent and little toxicity beyond three cases of grade 2 cataract and three of grade 1 blepharitis. Very low-dose schedules of about 4 Gy in two fractions are used to spare the lens and the tear gland, with retreatment if the lymphoma returns. Where local series have shown an association with Chlamydia psittaci, a course of doxycycline is a reasonable first step, and the same series shows that trying it first did not cost patients their response to radiotherapy afterwards. (IMRT / IGRT (modern external beam), Radiotherapy in lymphoma: involved-site fields, 24 Gy, 4 Gy and total skin electron therapy, Palliative radiotherapy)
• Disease beyond the orbit: Treated as any other marginal zone lymphoma: watched where it is causing no trouble, and treated with an anti-CD20 antibody alone or with chemotherapy when it is. The regimens, the thresholds for starting and the evidence are on the marginal zone and MALT lymphoma pages and in the treatment layer of this family. (Marginal zone lymphoma, Extranodal marginal zone lymphoma of mucosa-associated lymphoid tissue (MALT lymphoma), Rituximab, Bendamustine, Watch and wait in lymphoma: when the right treatment is none yet, Marginal zone lymphomas: ESMO clinical practice guidelines)

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