Comparison of MALT and non-MALT primary large cell lymphoma of the stomach: does histologic evidence of MALT affect chemotherapy response?

Background: Although the clinicopathologic features of low grade gastric MALToma (lymphoma of mucosa-associated lymphoid tissue) recently have been well delineated, the significance of identifying histologic evidence of MALT origin in a primary high grade gastric lymphoma is less clear. The authors sought to address this issue and, in particular, to clarify if MALT and non-MALT primary large cell gastric lymphoma might have a different response to systemic chemotherapy.

Methods: The authors reviewed the pathologic specimens of all patients who had a diagnosis of primary large cell lymphoma of the stomach and who had been treated primarily by systemic chemotherapy in our institutions January 1, 1988-December 31, 1998. The patients were divided into two groups by experienced hematopathologists, based on the presence or absence of histologic features suggestive of MALToma, including typical lymphoepithelial lesions and infiltration of characteristic centrocyte-like cells. Disease staging was done according to the AJCC/UICC system with Musshoff modification. The median number of gastric biopsies for each patient was 7 (range, 1-21).

Results: Seventeen patients with and 26 patients without histologic evidence of MALToma were identified. Clinical features were similar between the two groups except that a greater proportion of patients without evidence of MALToma had elevated levels of serum lactate dehydrogenase (50% vs. 12%, P = 0.01). The median duration of follow-up for the 43 patients was 46.5 months (range, 17-124 mos). All patients received standard systemic chemotherapy including anthracyclines or anthracenedione. The response rate was 88.2% for patients with evidence of MALToma and 57.7% for those without (P = 0.03). The 5-year overall survival rate was 80.5% for patients with evidence of MALToma and 48.9% for those without (P = 0.02). Multivariate analysis indicated that response to chemotherapy, disease stage (Stage I and II-1 vs. Stage II-2, III, and IV), and the presence of MALToma features were independent prognostic factors for overall survival.

Conclusion: The results of this relatively small study series suggested that the presence of histologic features of MALToma in patients with primary large cell gastric lymphoma might have been associated with a better response to systemic chemotherapy and a better prognosis. Further studies to consolidate this conclusion are necessary.