<prompt> The commonest site of lymphoma in the gastrointestinal system isSmall bowelStomachLarge intestineOesophagus  <response>: Stomach is the commonest site of lymphoma in the gastrointestinal system is Stomach55. Helicobacter pylori infection is the causative agent commonly. Other sites are small bowel30, colon10, ileocaecal region 5.Reference : page 856 SRBs manual of surgery 5th edition 