• Helicobacter pylori eradication as cancer treatment in gastric MALT lymphoma: Gastric MALT lymphoma is grown by a stomach bacterium, and killing the bacterium with a ten to fourteen day course of antibiotics cures most cases.
• Staging a lymphoma of the stomach or bowel: A lymphoma that starts in the stomach or bowel is staged by how deep it goes into the wall and how far along the lymph node chain it has travelled, not only by how many node regions are involved.
• Transformation of an indolent lymphoma: A slow-growing lymphoma can change into a fast-growing one.
• 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.
• Nodal and extranodal lymphoma: A lymphoma that starts in a lymph node is called nodal; one that starts in an organ is called extranodal.
• Endoscopy (EGD, EUS, ERCP): Looking inside a hollow organ with a camera on a flexible tube, taking biopsies and sometimes treating on the spot.
• 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.
• 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: Endoscopy with multiple biopsies from the abnormal area and from every region of the stomach, because the lymphoma is patchy and a single biopsy can miss it. Helicobacter pylori is sought by more than one method. Endoscopic ultrasound measures how deep the lymphoma goes, which predicts whether antibiotics alone will work; in a prospective comparison against the resected stomach it judged the depth correctly in 91.5 per cent of cases. Fluorescence in situ hybridisation for t(11;18) is done where it will change the plan. Staging uses the gastrointestinal system that counts depth and node involvement rather than the ordinary node-region count.

Biomarker results to ask for: Helicobacter pylori, by histology, urea breath test, stool antigen or serology; more than one test is used because treatment with acid suppression makes the biopsy unreliable, t(11;18)(q21;q21) giving BIRC3::MALT1, found in about 15 per cent, which predicts that eradication will not work, Depth of invasion of the stomach wall on endoscopic ultrasound, which predicts response to eradication, A monoclonal immunoglobulin heavy chain rearrangement, which often persists after histological remission and does not by itself mean treatment has failed, Trisomy 3 and trisomy 18, common across all marginal zone lymphomas, Large cells on the biopsy, which mean transformation to diffuse large B-cell lymphoma and change the treatment entirely.

Scans and tests linked to this cancer: Endoscopic ultrasound and EBUS systems, Histopathology & immunohistochemistry.

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

• First treatment: eradicate the bacterium: A standard eradication regimen of a proton pump inhibitor with two antibiotics, chosen by local resistance patterns, is the first treatment for Helicobacter pylori-positive disease and is also offered in negative disease, where a minority still respond. Success is confirmed by a breath or stool test after treatment, and the lymphoma is then followed by repeated endoscopy and biopsy over months, because regression is slow. In the prospective series of 120 patients with stage I disease, 80 per cent achieved complete histological remission and 80 per cent of those remained in continuous remission at a median follow-up of 75 months. (Helicobacter pylori eradication as cancer treatment in gastric MALT lymphoma, Endoscopy (EGD, EUS, ERCP), Watch and wait in lymphoma: when the right treatment is none yet, Staging a lymphoma of the stomach or bowel)
• Residual disease on a follow-up biopsy: Residual lymphoma on a biopsy after successful eradication is common and usually does not need treatment. In the same series, 17 per cent of those who had reached complete remission later showed histological residual disease; they were watched rather than treated, and all of them entered a second remission. A persisting monoclonal band in the immunoglobulin genes is also common and is not by itself a reason to treat. What does need action is growth, new symptoms, or large cells appearing on the biopsy. (Watch and wait in lymphoma: when the right treatment is none yet, Endoscopy (EGD, EUS, ERCP), Histopathology & immunohistochemistry)
• When antibiotics do not work, or cannot: Radiotherapy to the stomach at a low dose is the usual next step for disease that stays localised, and anti-CD20 antibody treatment, alone or with chemotherapy, for disease that has spread or that carries t(11;18) and is therefore unlikely to respond to eradication. Surgery has essentially no role at any stage, which is the main difference from gastric cancer. The regimens, the doses and the evidence are on the MALT lymphoma page and in the treatment layer of this family. (Extranodal marginal zone lymphoma of mucosa-associated lymphoid tissue (MALT lymphoma), Rituximab, Radiotherapy in lymphoma: involved-site fields, 24 Gy, 4 Gy and total skin electron therapy, Bendamustine, 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.