Overview
Lymphocytes are white blood cells that fight infection and live in lymph nodes and in the lining of the gut. Lymphoma happens when these cells grow out of control. GI lymphoma most often involves the stomach, followed by the small bowel and the colon. There are many types. Some are slow-growing (low grade), such as MALT lymphoma of the stomach, which is linked to Helicobacter pylori infection. Others, such as diffuse large B-cell lymphoma, grow faster and need prompt treatment. The type is decided by examining a tissue sample.
Symptoms
Ongoing belly pain or discomfort
Feeling full quickly, nausea or vomiting
Loss of appetite and unplanned weight loss
Fever, drenching night sweats and tiredness (sometimes called "B symptoms")
Black stools or signs of bleeding and anaemia, such as pallor and breathlessness
Diarrhoea or a change in bowel habit
Swollen glands in the neck, armpit or groin
Self-Care Tips
Follow-up visits and scans continue after treatment to watch for return of the lymphoma.
Emotional support matters. Ask your team about counselling or patient support groups.
When to See a Doctor
Seek medical care promptly if you notice: Sudden severe belly pain, a rigid belly, or fever with severe pain; Vomiting blood, black tarry stools, or fainting; Repeated vomiting with a swollen belly and no passage of wind or stool; Fever, night sweats and weight loss together.
Why it happens
The cause is often not known. Long-standing Helicobacter pylori infection is a recognised cause of stomach MALT lymphoma. Coeliac disease that is poorly controlled can be linked to a type of small bowel lymphoma. A weakened immune system (for example after organ transplant, with HIV, or from some immune-suppressing medicines) and some inflammatory conditions can raise the risk. Most people with these conditions will never develop lymphoma.
How common it is
GI lymphoma is uncommon compared with other digestive cancers. It can occur at any adult age, and certain types are more frequent in people with long-standing infection, coeliac disease or a weakened immune system.
How it is diagnosed
The diagnosis is made by biopsy, usually taken during an upper endoscopy or colonoscopy, and examined by a specialist pathologist with special stains to identify the lymphoma type. Blood tests, CT or PET-CT scans and sometimes a bone marrow test show how far it has spread (the stage). For stomach MALT lymphoma, testing for Helicobacter pylori is part of the work-up. A blood doctor (haematologist) and a gastroenterologist usually plan care together. Your doctor decides which tests you need.
Lifestyle and daily habits
Daily habits support you through diagnosis and treatment.
• Keep a record of symptoms such as fever, sweats, weight and bleeding, and bring it to appointments
• Take every course of treatment, including antibiotics for H. pylori, exactly as prescribed
• Report fever promptly during chemotherapy, because infections can become serious quickly
• Rest when you need to and stay gently active
• Do not smoke
Diet
The aim is to keep your weight and strength up during treatment.
• Eat small, frequent, energy- and protein-rich meals if appetite is poor
• Ask for a dietitian referral if you are losing weight
• During chemotherapy follow your team's food-safety advice, such as thoroughly cooking meat and eggs and washing produce
• If you have coeliac disease, keep strictly to a gluten-free diet
Medicines
Your haematology and gastroenterology team will choose treatment based on the type and stage of lymphoma.
• Antibiotics and acid-lowering medicine to clear H. pylori in stomach MALT lymphoma
• Chemotherapy and antibody-based treatments for faster-growing or more widespread lymphoma
• Medicines to prevent nausea and protect against infection are often given alongside treatment
• Do not stop or change treatment on your own, and tell your team about all other medicines and herbal products you take
Procedures and surgery
Procedures are used mainly for diagnosis and, in selected cases, to manage complications.
• Endoscopy and colonoscopy with biopsies confirm the diagnosis and track the response
• Repeat endoscopy is used to check that H. pylori has gone and that the lymphoma is responding
• Radiotherapy is sometimes used for localised disease
• Surgery is now needed mainly for complications such as perforation, bleeding or blockage
Latest science
For early stomach MALT lymphoma linked to H. pylori, treating the infection with antibiotics can lead to remission in many patients without any cancer treatment, and this is now the standard first step. Faster-growing types are usually treated with modern combination regimens, often including antibody medicines, and surgery is now needed less often than in the past.
Outlook
The outlook depends on the lymphoma type and stage. Low-grade types, especially stomach MALT lymphoma, often do very well and can sometimes be controlled for many years. Faster-growing lymphomas can often be cured or put into long remission with treatment, and starting early helps. Your haematology team can explain what to expect for your type.
Questions to ask your doctor
• What type and stage of lymphoma do I have?
• Is H. pylori involved, and will treating it be enough at first?
• What is the treatment plan and how long will it last?
• What side effects should I expect and which need urgent attention?
• How will you check that treatment is working?
• How often will I need follow-up after treatment?
Source and review
This guide comes from the Saudi Gastroenterology Association (SGA) patient library, prepared by the Approved for publication by SGA; individual clinician review is ongoing. Last reviewed: 2026-04-24. It is for education and does not replace your doctor's advice.
Frequently Asked Questions
What is GI Lymphoma?
How is GI Lymphoma diagnosed?
What is the outlook for GI Lymphoma?
When should I see a doctor about GI Lymphoma?
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