Gastric
lymphoma
Gastric lymphoma is an interesting disease and some aspects of the
management are controversial. It is first important to distinguish primary
gastric lymphoma from involvement in the stomach in a generalised lymphomatous
process. This latter situation is more common than the former. Unlike gastric
carcinoma, the incidence of lymphoma seems to be increasing. Primary gastric
lymphoma accounts for approximately 5 per cent of all gastric neoplasms.
Gastric
lymphoma is the most common in the sixth decade and the presentation is no
different from gastric cancer, the common symptoms being pain, weight loss and
bleeding. Acute presentations of gastric lymphoma such as haematemesis,
perforation or obstruction are not common. Primary gastric lymphomas are
B-cell-derived, the tumour arising from the mucosa-associated lymphoid tissue
(MALT). Primary gastric lymphoma remains in the stomach for a prolonged period
before involving the lymph nodes. At an early stage the disease takes the form
of a diffuse mucosal thickening which may ulcerate. Diagnosis is made as a
result of the endoscopic biopsy and seldom on the basis of the endoscopic
features alone, which are not specific.
Following
diagnosis adequate staging is necessary, primarily to establish whether the
lesion is a primary gastric lymphoma or part of more generalised process. A
CT
scan of the chest and abdomen and bone marrow aspirate are required, as well as
a full blood count.
Although
the treatment of primary gastric lymphoma is somewhat controversial, it seems
most appropriate to use surgery alone for the localised disease process. No
benefit has been shown from adjuvant chemotherapy, although some oncologists
contend that primary gastric lymphoma can be treated by chemotherapy alone.
Chemotherapy alone is appropriate for patients with systemic disease.
Some
of the more controversial aspects of gastric lymphoma concern the role of H.
pylori. Lymphocytes are not found to any degree in normal gastric mucosa but
are found in association with Helicobacter infection. It has also been
shown that early gastric lymphomas may regress and disappear when the Helicobacter
infection is treated (Issacson). This is an extremely surprising finding as
it suggests that the neoplasm, which is demonstrably monoclonal, may be a
response to the infective agent. It may be that the immunological response to
the organism, probably a T-cell-related process, is important in maintaining the
B-cell malignancy.
Gastric
involvement with the diffuse lymphoma
These patients are treated with chemotherapy, sometimes with dramatic
and rapid responses. Surgeons are frequently asked to deal with the
complications of gastric involvement. The two common complications are bleeding
and perforation. Both may occur at presentation but more usually may follow
the chemotherapy when there is rapid regression and necrosis of the tumour.
These operations can be technically very challenging and normally require
gastrectomy.