Mucosal-Associated Lymphoid Tissue Lymphoma in Southeast Asia: A 15-Year Retrospective Multicenter Study

<b>Objective:</b> To describe the epidemiology, survival rate, and prognostic factors of mucosal-associated lymphoid tissue (MALT) lymphoma. <b>Patients and Methods:</b> This investigation utilized the Thai Lymphoma Study Group (TLSG) registry to gather data on patients diagnosed with MALT lymphoma. The analysis included demographic details, therapeutic interventions, and survival statistics. <b>Results:</b> The TLSG registry prospectively included 8404 patients with lymphoma. Among them, marginal-zone lymphoma (MZL) was the second most common subtype, with 670 histologically confirmed cases, accounting for 8.0% of the total cohort. An analysis of the MZL subtypes showed that MALT lymphoma was the most common, accounting for 77.8% of the diagnoses. This was followed by nodal MZL at 17.5% and splenic MZL at 7.7%. The distribution of primary disease sites indicated that the ocular adnexa (49.2%), stomach (12.9%), and sinonasal region (12.5%) were the three most common locations. Three variables were found to be statistically significant predictors of survival in the multivariate analysis: ECOG performance status > 2, age exceeding 65 years, and involvement of more than two extranodal organs. These identified prognostic factors were further assessed for their effect on overall survival (OS) and progression-free survival (PFS). A risk classification was established: the low-risk group comprised patients with zero identified risk factors, whereas the high-risk group included patients who had any of the specified risk factors. A comparison of five-year survival rates showed significantly more favorable outcomes for low-risk patients who had a PFS of 83.3% (vs. 66.1%, <i>p</i> = 0.028) and an OS of 97.8% (vs. 76.7%, <i>p</i> < 0.001) compared to the high-risk group. <b>Conclusions:</b> In this cohort, where MZL was the second most common lymphoma and MALT lymphoma was the predominant subtype, our analysis revealed that patients with no risk factors experienced statistically significant improvements in both PFS and OS.