[Significance of C-myc expression in T-lymphoblastic lymphoma/leukemia and its relation with prognosis].

Abstract

To study the C-myc gene and protein in T lymphoblastic lymphoma/leukemia (T-LBL/ALL) and its relationship to prognosis. 60 cases of T-LBL/ALL with follow-up data were studied by using immunohistochemical EnVision method for CD1a, CD3, εCD3, CD7, CD10, CD34, CD43, CD45RO, CD99, TDT, CD20, CD23, MPO, Ki-67 and C-myc. 20 cases of reactive lymph nodes were selected as normal control group of C-myc gene and protein. Fluorescence in-situ hybridization (FISH) for C-myc gene (located on chromosome8q24) was performed to detect its breakage and gain. Among the 60 cases of T-LBL/ALL, immunohistochemistry results showed:the percentages of tumor cells expression of CD1a, CD3, εCD3, CD7, CD10, CD34, CD43, CD45RO, CD99 and TDT were 38.3% (23/60), 75.0% (45/60), 45.0% (27/60), 95.0% (57/60), 36.7% (22/60), 23.3% (14/60), 60.0% (36/60), 41.7% (25/60), 96.7% (58/60) and 93.3% (56/60). Separately, while CD20, CD23 and MPO were all negative. A figure of Ki-67 expression ≤ 80% was found in 36 cases and > 80% was found in 24 cases. The positive rate of C-myc protein was 66.7% (40/60) in 60 cases of T-LBL/ALL, was 0% (0/20) in 20 cases of reactivated lymphoid tissue (χ² = 26.67, P < 0.05). C-myc protein expression was positively correlated with the mediatinal width and Ki-67 index (P < 0.05). Fluorescence in-situ hybridization results showed that among the 60 cases of T-LBL/ALL, C-myc gene with breakage of 8q24 was detected in 6 cases (10.0%), and gains in 11 cases (18.3%). 20 cases of reactive lymph nodes were not occurred breakage and gains of C-myc gene. It is not significant between C-myc gene and protein expression (P > 0.05). In addition, in 60 cases of T-LBL/ALL, 12(20.0%) cases of C-myc protein and genetic abnormalities coexist. Log-rank analysis results: The prognosis of C-myc protein positive group was worse than negative group (P < 0.05). The relationship of C-myc gene and prognosis was not significant (P > 0.05). C-myc protein and genetic abnormality coexist is related with worse prognosis (P < 0.05). COX analysis results show that the C-myc protein positive group may be a independent poor prognosis factors (P < 0.05). C-myc may play an important role on the development of T-LBL/ALL. It may be a independent prognosis factors.