Prognostic value of immunohistochemical classification of diffuse large B-cell lymphoma into germinal center B-cell and non-germinal center B-cell subtypes

OBJECTIVE: To study the expression of germinal center B-cell (GCB)/activated B-cell like-related proteins to get optimal stratification of diffuse large B-cell lymphoma (DLBCL) patients, and correlate this with the established clinical and laboratory parameters.

METHODS: This study was conducted retrospectively on 30 archival paraffin tissue blocks of DLBCL. All patients were diagnosed between April 2004 and January 2007 at Ain Shams University Hospital and National Cancer Institute, Cairo, Egypt. All patients received anthracycline-based regimens, and none of them received rituximab immunotherapy. Each case included in this study was investigated by immunohistochemical reaction for multiple myeloma-1/interferon regulatory factor-4, B-cell/lymphoma 6, and cluster of differentiation10 monoclonal antibodies.

RESULTS: Patients were classified as GCB group (17 patients) and non-GCB group (13 patients). We found a statistically significant association between non-GCB phenotype and performance status (PS) more than 1, high lactate dehydrogenase (LDH) level, advanced international prognostic index (IPI), and poor patient outcome. Non-GCB phenotype, high LDH level, and PS more than 1 were all associated with increased mortality risk. The median survival time was 46.9 months in group A compared to 19.6 months in group B (hazard ratio[HR]=3.30; 95% confidence interval [CI]=0.52-21.10). Using multivariate Cox regression analysis, non-GCB phenotype was found to be the most predicting factor (HR=6.07; 95% CI=1.6-22.9; p=0.008).

CONCLUSION: The subclassification of DLBCL into GCB and non-GCB groups using immunohistochemistry may be useful for identifying those patients whose prognosis is so poor that more aggressive therapy can be given at the time of diagnosis.