Evaluation of immunohistochemical subtypes in diffuse large B-cell lymphoma and its impact on survival

Diffuse large B-cell lymphoma (DLBCL) is the most common type of non-Hodgkin lymphoma in Indian population. The disease could be divided into the prognostically important subtypes, germinal center B-cell (GCB)-like and activated B-cell-like, using gene expression profiling (GEP). The molecular subtype as defined by GEP could also be predicted by using immunohistochemistry (IHC) based algorithms using three biomarkers CD10, BCL-6, and multiple myeloma oncogene-1 (MUM1). It has been confirmed that patients belonging to the GCB subtype have a better outcome and survival than those belonging to the second subtype. The present study was conducted to study the prevalence of these two subgroups and their correlation with survival of the patients.

A total of 83 patients of DLBCL were included in the study. Hematoxylin- and eosin-stained sections were prepared from the paraffin-embedded tissue blocks. The staining for all the three antibodies was considered positive when more than 30% cells were stained with the respective antibody.

The results showed that 44 patients (53%) had GCB immunophenotype and 39 patients (47%) had non-GCB phenotype. However, no statistically significant difference in overall and disease-free survival was noted between the subgroups.

This study demonstrated that frequency of GCB subtype of DLBCL is significantly higher than the non-GCB subtype, and the non-GCB immunophenotype has better relapse-free survival 78% (standard error = 0.10) at the end of 3 years, while GCB has 56% (standard error = 0.23). Further studies should be performed with larger number of patients to show difference in clinical outcome between GCB and non-GCB subgroups.