Relapsed acute leukemia in children: Oman experience.

Acute leukemia (AL) is the most common malignancy in children in Oman. It accounts for over one-third of all childhood cancers, most of which (approximately 75%) are acute lymphoblastic leukemia (ALL). Over a decade, a total of 128 cases of childhood acute leukemia have been diagnosed and managed at Paediatric Haematology/Oncology Unit, Sultan Qaboos University Hospital, which is the national referral center of pediatric leukemia cases. A retrospective review of case notes was used to study all children with a diagnosis of acute leukemia from January 1993 to January 2003. All the cases were diagnosed using a bone marrow aspirate with morphological and immunophenotypic classification. Over this period, 24 cases relapsed. They were classified as per BFM group as "very early," "early," and "late" according to the time from diagnosis to first relapse and were divided into isolated bone marrow (BM), extramedullary site, and combined relapse. Sixteen percent of ALL cases and 58.6% of acute myeloid leukemia (AML) cases so far relapsed. Most of the AML cases relapsed very early on in treatment. Eleven patients had combined relapse in BM and extramedullary site (9 in the central nervous system, 1 in the testicles, and 1 in the eye). The overall outcome of these patients is very poor, and only 6 patients out of 24 are still alive. In conclusion, the relapse rates of childhood AL are more or less similar to those of other reports but the overall outcome is very poor. A large majority of the patients in this study are either very early or early relapsers. Future studies including genetic and molecular analysis may be able to explain the difference in clinical outcome of these relapsed AL cases.