Epstein Barr virus predicts outcome in pediatric B-cell Non Hodgkin lymphoma

PAOLA ANDREA CHABAY; DE MATTEO E; LARA J; LORENZETTI, M.; CAMBRA J; AVERSA, L.; PRECIADO, M. V.

Berlin

Congreso; European Hematology Association 14th Congress; 2009

European Hematology Association

Background: In Western countries malignant non-Hodgkin lymphomas (NHLs) represent the fourth most common childhood cancer, accounting for about 6% of pediatric malignancies. The majority of pediatric NHLs derives from B cells (B-NHL) and represents primary high-grade lymphomas. The 3 most prevalent entities are Burkitt lymphoma (43%), B-lymphoblastic lymphoma (7%), and diffuse large B-cell lymphoma (13%). EBV expression as well as some apoptosis markers has been related to prognosis in adult B-NHL, but little is known in pediatric B-NHL. Aim: To quantitatively assess EBV, bax, bcl2, Ki67 and activated caspase-3 (casp-3a) expression in B-NHL, and to correlate each one with patients’ event free survival. Methods: We analyze 40 pediatric B-NHL, 23 Burkitt lymphoma (BL) and 17 diffuse large B-cell lymphoma (DLBCL); age range 1 to 16 yrs, (median: 7 yrs); male:female ratio 5:3. Ki67, casp-3a, bax and bcl2 expression was assessed by immunohistochemistry, and EBV by EBERs in situ hybridization in formalin fixed-paraffin embedded lymph node biopsies. Results were expressed as (n° positive cells/field) / (nº total cells/field) × 100, in 10 high-power fields (x1000). Results: Ki67, casp-3a, bax and bcl2 were detected in 39/40 (97.5%), 34/40 (85%), 37/40 (92.5%) and 13/40 (32.5%) cases, respectively. Quantification of positive tumor cells for each cellular marker was: Ki67 1 to 97.6 % (median 55), casp-3a 0 to 15% (median 1.75), bax 0 to 99.1% (median 9.65) and bcl2 0 to 70.6 % (median 0).  Significant positive correlation was found only between bax/casp3a (r=0.4504, p=0.0035, Spearman’s correlation). The 5-year event-free survival of all patients was 65%. None of the cellular marker was associated with unfavorable outcome according to Kaplan Meier survival analysis, using each median as cut off points.  Sixteen out of 40 cases (40%) showed EBERs positive hybridization (8/23 BL, 35%; 8/17 DLBCL, 47%). EBV expression was not statistically associated with Ki67, casp-3a, bax and bcl2 positive staining; however it was significantly associated with a worse event-free survival (EFS) according to Kaplan Meier Survival analysis (p=0.0155, log rank test). Conclusions: High expression of Ki 67 and the proapoptotic protein bax together with casp-3a, indicate that high proliferation index could trigger apoptosis, and both are essential on pediatric B-NHL development. EBV expression in pediatric DLBCL is higher than the observed in the adult counterpart. EBV could be a cofactor of both pediatric DLBCL and BL lymphomagenesis. EBV presence was statistically associated with worse EFS, and predicts highly unfavorable prognosis in pediatric B-NHL, thus it could be used as prognosis factor for this pediatric malignancy.