Raya Saab1, Khaled Ghanem2, Sima Jeha3. 1. Children's Cancer Institute, American University of Beirut Medical Center, Beirut 1107 2020, Lebanon. Electronic address: Rs88@aub.edu.lb. 2. Basma Pediatric Oncology Unit, Al Bairouni Hospital, Damascus, Syria. 3. Department of Global Pediatric Medicine, St Jude Children's Research Hospital, Memphis, TN, USA.