Characteristics and Treatment Outcome of Childhood Acute Lymphoblastic Leukemia: Comparison Between Ethnic Populations in Israel

• Published in: Blood 2014-12, Vol.124 (21), p.2257-2257
• Main Authors: Elhasid, Ronit, Abramov, Aya, Arad -Cohen, Nira, Attias, Dina, Avrahami, Galia, Ballin, Ami, Ben Arush, Myriam, Bielorai, Bella, Burstein, Yoav, Elitzur, Sara, Gavriel, Hertzel, Kapelushnik, Joseph, Sthoeger, Dalia, Toren, Amos, Yaniv, Isaac, Wientraub, Michael, Nirel, Ronit, Izraeli, Shai, Stark, Batia
• Format: Article
• Language: English
• ISSN: 0006-4971; 1528-0020
• DOI: 10.1182/blood.V124.21.2257.2257

Background and aims: Differences in outcome and disease characteristics of childhood acute lymphoblastic leukemia (ALL) among ethnic groups were reported worldwide. We explored such differences among ethnic populations in Israel. Methods: Patient and disease characteristics and outcome were compared retrospectively among Jewish, Muslim, Bedouin, Druze, and Christian populations. Dose intensity and adherence to chemotherapy was measured by comparing dose and duration of treatment between the ethnic groups. Treatment duration was measured in days, from the first day of induction until the beginning of maintenance, compared to the scheduled time table according to the protocol, and expressed as percentage of delay. All data were retrieved from the Israeli National Center of Childhood ALL database after approval of the ethics committees of the participating institutions. Results: Between the years 1984-2011, 1286 patients aged 1-21 years were enrolled into 4 Israeli National Studies (INSs) for childhood ALL. The patients included 963 Jews (75%), 211 Muslims (16%), 54 Bedouins (4%), 28 Druze (2%) and 30 Christians (2%). In the first ALL INS-84 protocol (132 patients) the outcome of Muslims was inferior to that of the Jews in patients with pre-B ALL (10 years event free survival (EFS): 33.3%±13.6 Vs 68.8% ±5.3 (p=0.043)). The other ethnic groups were too small for statistical analysis. In the three subsequent ALL-BFM-based protocols since 1989: ALL-INS 89, 98, and 2003/7 the outcome improved with time for both Jewish and Muslim patients, abrogating the earlier group difference. In the combined latter 3 studies, the Bedouins had a poorer outcome compared to Jews, Muslims, Druze, and Christians with 5-year EFS of 60.3%±7.2%, 80.4%±1.4%, 77.3%±3.2%, 84.0%±7.3%, and 88%+6.8% (p=0.020), respectively. The difference was mainly due to higher relapse rates in high risk (HR) group (5 year cumulative incidence of relapse (CIR) of 85.7%, 30.3%, 29.4% (p=0.003) in the Bedouin, Jew and Muslim respectively) and in T ALL (5 year CIR of 45.8%, 16.9%, 13.9% (p=0.05) respectively). Higher rate of death in remission (DIR) due to infections was observed in the medium risk (MR) group (5 year DIR of 11%, 1.5%, 0.9% (p=0.005) in the Bedouin, Jew and Muslim respectively) and in pre-B ALL (10.9%, 1.3%, 2.1% (p=0.001) respectively). As opposed to the other ethnic groups the current study did not improve outcome of Bedouins. No major differences in clinical and leukemia cell characteristi