Prognostic Significance of BCL-6 Protein and KI-67 Monoclonal Antibody in Large Cell B-lymphoma Treated with Polichemiotherapy with or without Addition of Rituximab

Abstract

Introduction: Lymphomas are malignant neoplasms of lymphoid tissue characterized by heterogenecity in pathology and clinical symptomatology. Diffuse large cell lymphoma (DLCL) is the most common type of non-Hodgkin's lymphoma (NHL), accounting for almost 35-40% of all cases of NHL. Aim: To analyse the expression of Ki-67 i bcl-6, in large cell lymphoma tissue, treated with CHOP and CHOP+R protocol, and to evaluate the level of therapeutic response and the duration of progression free survival of the disease in patients with diffuse large cell lymphoma, treated by therapeutic protocols CHOP and CHOP+R. Methods: For analysis of both Ki-67 and bcl-6 we used criterion for positivity of >10% expression in lymphoid tissue. Results: The median of precentual expression of bcl-6 in total sample was 15,5% with interquartile range of 5,5% and 54,5%, and with minimum of 0% and maximum of 99%. Considering the criterion of bcl-6 positivity with 10% positive lymphoma cells, in total sample there was 29/50 (48,3%) bcl-6 positive cells. Comparing the two different treatments, there was no difference in level of bcl-6 expression. (Mann-Whitney; U=398; p=0,44). There was also no difference in incidence of bcl-6 positive patients (considering the criterion of >10% expression) between two types of treatment (X2=0,60; df=1; p=0,44). The median value of procentual Ki-67 expression in total sample was 59% with interquartile range of 33% to 74%, and minimum from 11% to 96%. All the patients were Ki-67 positive, considering the criterion of >10% expression in lymphoid tissue. Compared within two therapeutic groups, there was no difference in level of Ki-67 expression (Mann-Whitney; U=403,5; p=0,49). Separate Cox analiysis for both treated groups of patients was made to evaluate the separate prognostic influence of bcl-6 and Ki-67 on the duration of progression free survival of the disease. In the group of patients treated with CHOP protocol niether bcl-6 (OR=0,99; %CI=0,96-1,02; p=0,44) nor Ki-67 (OR=0,99; %CI=0,97-1,02; p=0,60) showed significant influence on duration of progression free survival of the disease. In the group of patients treated with CHOP+R protocol, there was also no significant influence of bcl-6 (OR=0,93; %CI=0,82-1,07; p=0,32) and Ki-67 (OR=1,02; %CI=0,97-1,08; p=0,42) on duration of progression free survival. Conclusions: These data suggest that Ki-67 and bcl-6 expression in tumor tissue can not be used as indicators for the level of therapy response and progression-free period in large cell B-lymphoma treated with polichemiotherapy with or without addition of Rituximab.