Gastric lymphoma

Classification

Described as primary gastric lymphoma if the stomach is the exclusive or predominant site of disease

Diffuse large B cell lymphoma - DLBCL (45-60%)
- Generally primary lesions, but can also occur as progression from less aggressive lymphomas such CLL, small lymphocytic lymphoma, follicular lymphoma, or MALT lymphoma
- Associated with immunodeficiency and H. pylori infection
- Fairly high-grade
Gastric Mucosa-Associated Lymphoid Tissue (MALT) lymphoma (40-50%)
- Lower grade than DLBCL
- B cell lineage
- Usually preceded by H. pylori gastritis (in almost all cases). B cells are chronically activated in stomach, forming a MALToma, which can transform into lymphoma.
- Characterised by translocations at:
  - T(1;14)
  - T(3;14)
  - T(11;18)
  - T(14;18)
Peripheral T cell lymphoma (1-4%)
Mantle cell lymphoma (<1%)
Follicular lymphoma (<1%)
Usually occurs in gastric antrum, but can arise from anywhere

Vague symptoms
- Epigastric pain
- Early satiety
- Fatigue
- B symptoms - only about 10% of patients

Endoscopy
- Biopsy is indicated for all patients
- Test for H. pylori (probably need to also confirm with serologic testing)
- EUS can be used to determine depth of invasion and evaluate for lymph node involvement
Upper airway examination
- Look for distant disease - Waldeyer tonsillar ring
Bone marrow biopsy
CT chest/abdo/pelvis
- Routine staging
PET/CT (FDG)
- Dependent on subtype
- Usually done for DLBCL staging

Chemotherapy
- Most commonly R-CHOP
- Associated with a 5% rate of gastric perforation and GI bleeding
Indications for surgery
- Symptomatic recurrence after treatment failure
- Complications (bleeding, gastric outlet obstruction, perforation)
MALT
- Must evaluate for H. pylori infection
- Early-stage MALT and active H. pylori infection may be treated by eradication alone - successful eradication results in remission for 75%, but need repeat endoscopy in 2 months and 6 monthly endoscopy for 3 years to document regression
- Predictors of failure from eradication alone:
  - Trans-mural tumour extension
  - Nodal involvement
  - Transformation into a large cell phenotype
  - Nuclear BCL-10 expression
- MALT and H. pylori negative:
  - Consider radiotherapy if all involved sites can be encompassed in a single field
  - Otherwise chemotherapy
- Risk factors for poor prognosis:
  - Age >=70
  - Stage IV disease
  - Elevated LDH
  - 5 year survival of 98.7% for no risk factors, 93.1% for one risk factor and 64.3% for two or three risk factors