The Prognostic Value of International Prognostic Index and MIB-1 Immunostaining of Peripheral Lymphoid Tissues and Bone Marrow in Patients with High-Grade Non-Hodgkin's Lymphoma

ling index and with the known clinical variables included within the IPI. Patients with high intermediate or high IPI who expressed high Ki-67 labelling index had a worse overall survival compared with patients with low or low intermediate IPI and low Ki-67 index (p < 0.001). BM in- filtration as detected by MIB-1 was correlated in univari- ate analysis (p = 0.04), although not confirmed in multi- variate analysis, with poor survival. Conclusion: In conclusion, the MIB-1 monoclonal antibody immunostain- ing appears to be a simple and reproducible method of de- termining tumour proliferative index and provides useful prognostic information in patients with high-grade NHL. We recommend using apoptotic markers in addition for proper assessment of the impact of detecting MIB-1 posi- tive cells in BM on disease outcome. ABSTRACT Background: Cell kinetic data are important indicator of the aggressiveness of tumour and clinical response. The Ki-67 antigen plays a pivotal role in maintaining cell pro- liferation and the expression of this antigen was found to be a valuable indicator for aggressive disease in a variety of neoplastic disorders. Aim of the study: This study aimed to assess the prognostic significance of the expression of Ki-67 antigen in peripheral lymphoid tissues and bone marrow, using the monoclonal antibody MIB-1 that is ap- plicable in formaline-fixed paraffin embedded samples in cases with high-grade non-Hodgkin's lymphomas. Materi- al and methods: The MIB-1 immunostaining was per- formed on 96 samples from 48 patients with high-grade non-Hodgkin's lymphomas. The study was performed on tissue sections, nodal or extranodal, as well as on BM smears or BM paraffin embedded sections of same pa- tients. Ki-67 index was determined using image analyzer. Results: Forty-five out of the studied 48 cases (93.8%) were positive with a median labelling index of 20.425% (Range, 0-58%). We were able to detect bone marrow in- volvement by detecting MIB-1 positive cells in BM sam- ples of 29 patients who were not morphologically diag- nosed to have BM infiltration. There was a strong correlation between BM positivity for Ki-67 and Ki-67 la- belling index (p < 0.001). Twenty-eight (58.3%) out of the studied 48 cases achieved complete remission (CR). The median duration of CR was 35 months (range, 8-42 months) and the overall survival at 48 months was 35.4% (median 22 months, 95% CI, 13-31 months). The median Ki-67 index (20.425%) was chosen as a cut-off level for statistical analysis of the variables that influence clinical outcome. The probability of inducing CR was associated with low and low intermediate International Prognostic In- dex (IPI) whereas a low growth fraction was associated, al- though not significant, with a trend toward a higher prob- ability of inducing a CR. In univariate analysis, high MIB- 1 labelling index and increased IPI were associated with shorter duration of complete remission and overall survi- val time. Multivariate analysis showed that an extended overall survival time was associated with low MIB-1 label-