Contents lists available at ScienceDirect Cancer Epidemiology journal homepage: www.elsevier.com/locate/canep Incidence trends of childhood acute lymphoblastic leukemia in Saudi Arabia: Increasing incidence or competing risks? Wasil Jastaniah a,b, *, Mohammed F. Essa c,d,e , Walid Ballourah f , Ibrahim Abosoudah g , Saad Al Daama h , Ali H. Algiraigri i , Ibrahim Al Ghemlas j,k , Mohammad Alshahrani l , Abdulrahman Alsultan m a College of Medicine, Department of Pediatrics, Umm AlQura University, Makkah, Saudi Arabia b Princess Noorah Oncology Center, Ministry of National Guard - Health Affairs, Jeddah, Saudi Arabia c King Abdullah Specialist Children's Hospital, Riyadh, Saudi Arabia d College of Medicine, King Saud bin Abdulaziz University for Health Sciences, Riyadh, Saudi Arabia e King Abdullah International Medical Research Center, National Guard Health Affairs, Riyadh, Saudi Arabia f Department of Pediatric Hematology /Oncology, Comprehensive Cancer Center, King Fahad Medical City, Riyadh, Saudi Arabia g Department of Oncology, King Faisal Specialist Hospital & Research Center, Jeddah, Saudi Arabia h King Fahad Specialist Hospital, Dammam, Saudi Arabia i Pediatric Hematology/Oncology Section, Department of Hematology, College of Medicine, King Abdulaziz University, Jeddah, Saudi Arabia j Faculty of Medicine, Alfaisal University, Riyadh, Saudi Arabia k King Faisal Specialist Hospital & Research Center, Riyadh, Saudi Arabia l Pediatric Hematology/Oncology/BMT, Prince Sultan Military Medical City, Ministry of Defiance, Riyadh, Saudi Arabia m Department of Pediatrics, College of Medicine, King Saud University, Riyadh, Saudi Arabia ARTICLE INFO Keywords: Childhood Acute lymphoblastic leukemia Incidence Saudi Arabia ABSTRACT Introduction. The incidence of childhood acute lymphoblastic leukemia (cALL) varies between countries likely as a result of competing risks including infections, access-to-care, socioeconomic influences, and/or ethnicity. However, little is known about disease burden in high-income Arab countries offering free-of-charge healthcare. The hypothesis was that, due to population characteristics (young age, high fertility and parental consanguinity rate), the incidence of cALL in Saudi Arabia is equal or higher than that observed in high-income Western countries. Methods. Saudi databases were used to calculate the incidence of cALL from 2001 to 2014. Incidence trends over time of children with ALL, 14-years of age or younger, were analyzed and compared with those reported in USA. Results. The age-adjusted incidence over the years was lower in Saudi Arabia compared to USA. However, the incidence trend of cALL in Saudi Arabia was increasing at a rate higher than that observed in USA (p < 0.001). The overall incidence of cALL in Saudi Arabia increased from 1.58/100,000 in 2001 to 2.35/100,000 population in 2014. The median annual increase was 4.58 %. The incidence in males increased from 1.88 to 2.71/100,000, and from 1.21 to 1.86/100,000 population in females. Conclusions. The reported incidence of cALL in Saudi Arabia is rapidly increasing. The increasing trend may reflect evolving socioeconomic structure, improved access-to-cancer care, and improved diagnosis/ reporting capacity. This highlights the need for better understanding of cALL causes and the need for the formation of separate national pediatric cancer registries in different countries to monitor childhood cancer incidence trends. https://doi.org/10.1016/j.canep.2020.101764 Received 24 December 2019; Received in revised form 14 May 2020; Accepted 4 June 2020 Abbreviations: ALL, Acute lymphoblastic leukemia; CRR, Cancer Registry Reports; CDC, Center for Disease Control; NA, Not applicable; USCS, United States Cancer Statistics ⁎ Corresponding author at: Umm AlQura University and Princess Noorah Oncology Center, Ministry of National Guard - Health Affairs, P.O.BOX 9515, Jeddah, 21423, Saudi Arabia. E-mail address: wasilj@yahoo.com (W. Jastaniah). Cancer Epidemiology 67 (2020) 101764 1877-7821/ © 2020 Elsevier Ltd. All rights reserved. T