Higher Rates of t(11;18) in Chinese Patients with Transformed Type of MALT Lymphoma Suggest Novel Pathways for Progression of the Disease.

Previous reports suggest that the prevalence and potential etiological factors of some types of lymphoma in China may be different from that reported in other countries. Our previous work in analyzing cell origin of 53 diffuse large B-cell lymphoma (DLBCL) patients demonstrated that Chinese patients have higher Non GC (%) DLBCL than GC(%) origin compare with the reports from Western countries (PMID: 16202261). In this study, we continued our exploration on potential differences between Chinese patients with mucosa-associated lymphoid tissue (MALT) lymphoma and patients reported from other countries. Several evidences suggest that gastric MALT lymphoma acquired as a consequence of Helicobacter pylori (H. pylori) infection and 80–90% patients with no t(11;18) chromosome translocation achieved the complete remission (CR) after receiving antibiotics therapy to eradicate H. pylori. But the patients with MALT, who have the t(11;18) and the nuclear expression of BCL-10, are barely responsive to the antibiotic therapy. Therefore, detection of the expression of t(11; 18) and BCL-10 nuclear expression in the patients with MALT lymphoma is of clinical significance in selection of H. pylori eradication regimen, predicting the clinical progression, and assessing the prognoses of the disease. In this study, we detected the t(11;18) chromosome translocation in different stages of MALT lymphoma. We established a RT-PCR with a method of short-length amplification by modifying that reported in preparation of RNAs from the paraffin-fixed tissue followed by molecular analysis of the genotype of the patients with MALT lymphoma. We examined the expression of API2-MALT1 in a large cohort of patients with lymphomas including 100 MALT lymphomas and 83 DLBCL cases, and analyzed the differences in the detection rates of API2-MALT1 fusion transcripts and BCL-10 nuclear expression among different MALT location. Our results showed the five key findings, including

• higher detection rates of t(11;18) (21.13%) in Chinese patients with transformed MALT lymphoma,

• lower detection rates of t(11;18) (15.79%) in stomach MALT lymphoma,

• different organ localizations of MALT lymphoma in Chinese patients,

• higher nuclear expression rates of Bcl-10 in low grade MALT (51.72%), and

• lower response rates (50% CR, and 50% PR) to anti-H. pylori therapy, suggest novel pathways for low-grade MALT lymphoma to be progressed into transformed MALT lymphoma.

This study also suggests that amplification of shorter length of PCR products from the paraffin-fixed tissues increases the sensitivity, which is significant in improving selection of therapeutic regimen and assessing the prognoses of disease. Also, in Chinese patients with MALT lymphoma, Bcl-10 nuclear expression may be independent of t(11;18) translocation, and may also play primary roles in MALT pathogenesis rather than “supporting roles” for t(11;18). Future international collaboration is needed to clarify that whether this new model fits patients with other ethnic backgrounds in addition to Chinese patients.