Gastric lymphoma and gastrointestinal stromal tumours (GISTs) are rare
malignancies of the upper gastrointestinal tract. The most common
gastric lymphoma are low-grade
marginal zone B-cell lymphoma (MZBCL) of MALT type. They develop as a consequence of chronic Helicobacter pylori
infection, the histological hallmark are lymphoepithelial lesions. In early stages of disease, H. pylori eradication alone may lead to complete
lymphoma remission in up to 75% of cases. Nonresponder or locally advanced
lymphoma should be treated with
radiation therapy. Advanced
lymphoma may be treated with the
nucleoside analogon
cladribine within clinical trials. Based on clinical and novel molecular markers a risk stratification and a prediction of response to
therapy might be possible in the future. GISTs are mesenchymal tumours that characteristically express CD-117 (c-kit). They are mostly localized in the upper gastrointestinal tract and are frequently diagnosed in an advanced stage. Conventional
chemotherapy is ineffective. For resectable non-metastasized tumours surgical
therapy is the treatment of choice.
Imatinib is the first and so far only effective systemic
therapy which is presently indicated in irresectable or metastasized GISTs. More than 80% of patients respond to
imatinib therapy either with partial remission or stable disease. FDG-PET plays an important role in the early prediction of response to
imatinib therapy. The optimal dosage and
duration of treatment and the role of
imatinib as adjuvant or neo-adjuvant
therapy for GISTs remains to be defined.