In a discussion of stomach bacteria and lymphoma, there is really only one bacterium and one subtype of lymphoma to discuss: a resilient, spiral shaped thing called Helicobacter pylori (H pylori) and gastric mucosa-associated lymphoid tissue (MALT) lymphoma.
Infection by this little bacterium is believed to be responsible for as many as half of all stomach cancers, and it is strongly linked to MALT lymphoma. According to the American Cancer Society, long-term infection by H pylori can cause ulcers in the stomach and other damage, though most people who are infected with it do not have any serious problems.
Infection by H pylori is extremely widespread, with as many as two-thirds of the population believed to be infected. It is believed to be spread either by contaminated ground water or food, or it can be transmitted from person to person orally.
Gastric mucosa-associated lymphoid tissue (MALT) lymphoma is a non-Hodgkin's lymphoma of B-cell origin that is very much unlike virtually every other lymphoma subtype.
Since MALT lymphoma has a known cause — the bacteria — that alone separates it from the other subtypes, but the disease is also treated much differently. Instead of combination chemotherapy, doctors treat MALT lymphoma with antibiotics. It is after all caused by bacteria, and antibiotics can effectively eliminate H pylori from the patient's system.
To that end, MALT lymphoma is a highly treatable disease and is often found in the early stages.