OBJECTIVETo investigate the role of t (14; 18) chromosomal translocation and bcl-2 amplification in classification, clinical staging and prognostic evaluation of diffuse large B cell lymphoma (DLBCL).

METHODSSixty cases of DLBCL were included in this investigation. Microdissection of the lymphoma tissue was performed. Tissue microarray and in-situ fluorescence hybridization technique were used to detect t (14; 18) and bcl-2 amplification. The phenotypes of either germinal center B-cell-like (GCB) or non-germinal center B-cell-like (non-GCB) were determined by immunohistochemistry including CD20, CD10, bcl-6 and MUM1 (S-P method) using the tissue microarray format. Clinical staging and therapeutic response were obtained by medical record review. The relationships among different parameters were analyzed by appropriate statistical methods.

RESULTSAmong 60 cases of DLBCL, bcl-2/IgH was positive in 10 cases and bcl-2 gene amplification was detected in 18 cases. Overall, 29 (48.3%) cases were GCB and 31 (51.7%) cases were non-GCB. The t (14; 18) was seen in 8 (80.0%) cases of GCB and 2 (20.0%) of non-GCB. The difference was statistical significance (P = 0.031). Over-expression of bcl-2 was seen in all cases having both t (14; 18) and bcl-2 gene amplification. Of thirty-six patients who underwent routine CHOP treatment, bcl-2 gene amplification was seen in 13 cases. In these cases, the rates of complete remission, partial remission and no change were 3 (23.1%), 4 (30.8%) and 6 (46.2%) respectively, and the clinical stages were stage I - II (1 case, 7.7%) and stage III - IV (12 cases, 92.3%). The clinical stages and therapeutic response were significantly different between the bcl-2 amplification cases and those without (P = 0.046 and P = 0.019, respectively).

CONCLUSIONST (14; 18) and/or bcl-2 gene amplification can lead to an over-expression of bcl-2 protein. The bcl-2 gene amplification correlates with worse therapeutic efficacies and advanced clinical stages. The reason for the correlation between bcl-2 over-expression and the prognosis is unclear, although it may be explained by different mechanisms that lead to bcl-2 over-expression. Detection of t (14; 18) chromosome translocation by FISH can be helpful in the classification of DLBCL.