A systematic review and meta-analysis of thymic mucosa-associated lymphoid tissue lymphoma

BACKGROUND: Mucosa-associated lymphoid tissue (MALT) lymphoma of the thymus is a rare disease. The present meta-analysis aims at accumulating current evidence to explore the clinical characteristics, treatments, and prognoses of thymic MALT lymphoma. METHODS: We searched seven databases for studies published between the start date of database establishment and September 15, 2021. We included studies of patients with histological diagnoses and excluded those without data specifically on thymic MALT lymphoma. The quality was analyzed using an assessment tool. All data were tabulated. Pooled proportion was obtained using random-effects model. Statistical analysis was performed on R statistic software. RESULTS: Overall, 52 case reports and 13 case series were eligible. The quality of case reports was inferior to that of case series in terms of selection (P<0.001). Based on the analysis of patients in the case reports, age, gender, concurrent diseases, and tumor size did not differ between limited-stage and advanced-stage cases. Surgery is the mainstay to treat thymic MALT lymphoma. The surgical approach and extent did not influence the occurrence of events. Patients at Ann Arbor stage I were prone to not receiving postoperative therapy (P=0.011), though it may not reduce the occurrence of events (P=0.637). The five-year overall survival (OS) rate and five-year progression-free survival (PFS) rate were 97.2% and 88.4%, respectively. Patients with advanced-stage disease were more likely to suffer events (P=0.009). CONCLUSIONS: Thymic MALT lymphoma is an extremely rare disease with a favorable prognosis. Currently available evidence is insufficient to draw solid judgments about treatment and prognosis. However, patients may benefit if thymectomy is chosen as the primary treatment. In some patients, lymph node sampling or dissection should be considered. In addition, if the patient is at an advanced-stage, postoperative therapy should be considered.