Contributions
Abstract: PB2070
Type: Publication Only
Background
Burkitt leukemia (BL) constitutes around 13.5% of pediatric mature B-cell non Hodgkin's lymphoma. It is characterized by translocation involving the MYC gene to one of the immunoglobulin genes. The clinical significance of secondary chromosomal abnormalities associated with this characteristic translocation remains unknown.
Aims
We aim to analyze the impact of secondary chromosomal abnormalities on treatment outcome in pediatric Burkitt leukemia.
Methods
Patients with BL presenting to Children Cancer Hospital in Egypt-57357 (CCHE) from July 2007 till end of December 2015, were reviewed for karyotyping, cMYC status by FISH using break apart probes, and secondary chromosomal abnormalities. These results were correlated with survival analysis.
Results
Eighty-seven BL patients were diagnosed and treated during the study period according to the FAB/LMB 96 protocol. Majority were males (77.3%) and above 10 years of age at presentation (42%). Associated central nervous system involvement was diagnosed in 32.9% of the patients. LDH more than 2 times the upper limit was seen in 79.5%, and 52.3% of the patients suffered from tumor lysis syndrome at presentation. Informative karyotype for 66 patients demonstrated translocation of the MYC and IGH genes in 54 patients (86%) while translocation of the IGK and IGL were found in 2 (3%) and 7 (11%), respectively. Secondary chromosomal abnormalities were detected in 40 (60%) patients, with 5 or more abnormalities in 4 patients, 3 chromosomal abnormalities in 12 patients, and 2 chromosomal abnormalities in 20 patients. The most common secondary chromosomal abnormality was duplication of chromosome 1q which was found in 16 patients. Other secondary chromosomal abnormalities included structural abnormality of chromosome 14q other than MYC translocation (6 patients), chromosome 6q deletion (4 patients), chromosome 13q deletion (3 patients), marker chromosome (3 patients), loss of chromosome 17p(2 patients), isochromosome 9q (2 patients), translocation of chromosome 13, trisomy 13 and trisomy 9 in one patients each. Relapse or tumor progression on chemotherapy was seen in 16% of the whole group of patients. The 5 year OS was 57.7%, while 5 year EFS was 51.6%. When comparing incidence of relapse in relation to complex karyotype, we found that nine out of 16 (56.2%) patients having complex karyotype experienced relapse whereas relapse occurred in only 6 (12.5%) patients having non-complex karyotype (p-value= 0.005)
Conclusion
The frequency of secondary chromosomal abnormalities in our series is in concordance with other publications with duplication 1q being the most common. followed by deletion 6q, 13q, and 17p. Complex karyotype was significantly associated with higher incidence of relapse and poor outcome.
Session topic: 18. Non-Hodgkin & Hodgkin lymphoma - Biology
Keyword(s): MYC, Chromosomal abnormality, Burkitt's lymphoma
Abstract: PB2070
Type: Publication Only
Background
Burkitt leukemia (BL) constitutes around 13.5% of pediatric mature B-cell non Hodgkin's lymphoma. It is characterized by translocation involving the MYC gene to one of the immunoglobulin genes. The clinical significance of secondary chromosomal abnormalities associated with this characteristic translocation remains unknown.
Aims
We aim to analyze the impact of secondary chromosomal abnormalities on treatment outcome in pediatric Burkitt leukemia.
Methods
Patients with BL presenting to Children Cancer Hospital in Egypt-57357 (CCHE) from July 2007 till end of December 2015, were reviewed for karyotyping, cMYC status by FISH using break apart probes, and secondary chromosomal abnormalities. These results were correlated with survival analysis.
Results
Eighty-seven BL patients were diagnosed and treated during the study period according to the FAB/LMB 96 protocol. Majority were males (77.3%) and above 10 years of age at presentation (42%). Associated central nervous system involvement was diagnosed in 32.9% of the patients. LDH more than 2 times the upper limit was seen in 79.5%, and 52.3% of the patients suffered from tumor lysis syndrome at presentation. Informative karyotype for 66 patients demonstrated translocation of the MYC and IGH genes in 54 patients (86%) while translocation of the IGK and IGL were found in 2 (3%) and 7 (11%), respectively. Secondary chromosomal abnormalities were detected in 40 (60%) patients, with 5 or more abnormalities in 4 patients, 3 chromosomal abnormalities in 12 patients, and 2 chromosomal abnormalities in 20 patients. The most common secondary chromosomal abnormality was duplication of chromosome 1q which was found in 16 patients. Other secondary chromosomal abnormalities included structural abnormality of chromosome 14q other than MYC translocation (6 patients), chromosome 6q deletion (4 patients), chromosome 13q deletion (3 patients), marker chromosome (3 patients), loss of chromosome 17p(2 patients), isochromosome 9q (2 patients), translocation of chromosome 13, trisomy 13 and trisomy 9 in one patients each. Relapse or tumor progression on chemotherapy was seen in 16% of the whole group of patients. The 5 year OS was 57.7%, while 5 year EFS was 51.6%. When comparing incidence of relapse in relation to complex karyotype, we found that nine out of 16 (56.2%) patients having complex karyotype experienced relapse whereas relapse occurred in only 6 (12.5%) patients having non-complex karyotype (p-value= 0.005)
Conclusion
The frequency of secondary chromosomal abnormalities in our series is in concordance with other publications with duplication 1q being the most common. followed by deletion 6q, 13q, and 17p. Complex karyotype was significantly associated with higher incidence of relapse and poor outcome.
Session topic: 18. Non-Hodgkin & Hodgkin lymphoma - Biology
Keyword(s): MYC, Chromosomal abnormality, Burkitt's lymphoma