Acute lymphoblastic leukaemia (ALL) in Hong Kong children: treatment outcome from 1993 to 2012

Abstract

PURPOSE/OBJECTIVE: To study demographic features of ALL and treatment outcome over past 20 years in Hong Kong. MATERIALS AND METHODS: HKPHOSG conducted 4 clinical trials on ALL since 1993, namely HKALL93, HKALL97, IC-BFM ALL 2002, and CCLG2008. Data were collected prospectively and follow-up of all recruited cases until Dec 2012. RESULTS: 624 patients were recruited into above studies and another 26 patients recruited into 3 international studies (EsPhALL and Interfant). Each trial ran for 58-64 months, CCLG 2008 study is still on-going. Number of subjects recruited were 152 (ALL93), 171 (HKALL97) and 175 (IC-BFM2002). There were no significant changes in demographic features including median age (4.9-5.6 years), presenting WBC (10.2-18.1), T cell (8-13%) at diagnosis. CNS leukaemia at presentation was 0.5-2%, and CNS 2 in recent 2 studies was 6%. Ph+ or BCR-ABL positive was 2.8%, E2A-PBX 4.3%, TEL-AML1 19.3%, hyperdiploidy 16%. Using NCI stratification, 59.5% patients belonged to standard risk. 91.4% had good prednisone response and CR rate 95.2-98.9%. Induction death was 2.2%, and similar over the 2 decades. Relapse rate decreased from 40.1% to 17.1%, death rate decreased from 26.3% to 12%, CNS relapse rate decreased from 5.5% to 0.8% despite reduction of cranial radiotherapy from 24.3% to 14.3%. 63 patients (10.1%) received allogeneic SCT, 20 patients received SCT in CR1. 5 year OS was 78.9%, 85.9% and 88.5%, EFS was 62.6%, 78.4% and 80% for HK93, 97 and 2002 studies respectively. 10 year OS was 76.2% and 82.9%, 10 year EFS was 56.3% and 76.9% for HK93 and 97 studies. 9 patients developed second malignancy. CONCLUSIONS: There was no change in demographic features of ALL in past 2 decades. Addition of delayed intensification improved EFS by 20%. Reduction of cranial RT did not increase CNS relapse when optimal systemic and intrathecal therapy administered. Acknowledgement: Children Cancer Foundation support for data manager.