Primary gastrointestinal lymphoma in Japan: a clinicopathologic analysis of 455 patients with special reference to its time trends.

Background: An optimal treatment modality for patients with primary gastrointestinal lymphoma has not yet been established. This study aimed to elucidate the clinicopathologic features of this disease and the influence of therapeutic modalities on the prognosis in Japanese patients

Methods: The clinicopathologic features of 455 patients with primary gastrointestinal lymphoma were investigated retrospectively regarding treatment modalities and time trends.

Results: This study comprised 342 patients (75%) with gastric lymphoma, 96 patients (22%) with intestinal lymphoma, and 17 patients (4%) with both gastric and intestinal lymphoma. Two hundred thirty-one (51%) patients were classified as having low-grade B-cell lymphoma including 200 marginal zone lymphoma of mucosa-associated lymphoid tissue (MALT) type, 185 (41%) patients were classified as having high-grade B-cell lymphoma including 76 diffuse large cell lymphoma plus MALT lymphoma, and 39 (9%) patients were classified as having T-cell lymphoma. The frequency of nonsurgical treatment, including Helicobacter pylori eradication, chemotherapy, and radiation, increased during the latest decade. Patients who received nonsurgical treatment showed a better overall survival than those treated by surgery, but event-free survival did not differ between two groups. Cox multivariate analysis revealed that early stage, younger age, gastric localization, B-cell phenotype, and absence of B symptoms were independent prognostic factors for better overall and event-free survivals. Mucosa-associated lymphoid tissue-derived lymphoma was also an independent prognostic factor for event-free survival, but not for overall survival.

Conclusions: Nonsurgical treatment may be an optimal therapeutic modality for patients with primary gastrointestinal lymphoma.