Li CK1, Yuen HL2, Ha SY3, Li CK4, Lee ACW5, Shing MMK1, For the Hong Kong Paediatric Haematology & Oncology Study Group.

1Prince of Wales Hospital, 2Queen Elizabeth Hospital, 3Queen Mary Hospital, 4Princess Margaret Hospital, 5Tuen Mun Hospital, Hong Kong, China


Objectives: To study the treatment result of paediatric ALL patients using a unified treatment protocol in Hong Kong.

Method: All ALL patients between 1 to 15 years diagnosed in Hong Kong from January 1993 to October 1997 were recruited in this multicentre study. Patients were stratified into standard risk (SR) , intermediate risk (IR) and high risk (HR) according to age, initial white cell count (WBC), immunophenotyping and cytogenetics. All received a 3-drug induction followed by a 5-days early and late intensification at week 5 and 20. High risk patients were treated with 3rd intensification at week 35 as well. CNS prophylaxis was intrathecal methotrexate (MTX) in SR, high dose MTX (6-8 g/m2) for 3 doses and IT MTX for IR, and 18 Gy CNS radiotherapy for HR.

Result: 146 patients were recruited and analysed. The median age at diagnosis was 4.9 years, with 59.8% between 1-6 years, and 19.3% were older than 10 years. The median WBC was 18 x109/L with 52% < 20 x109/L. Common ALL constitute 61.8% and T-cell occurred in 9.2%. Hyperdiploidy occurred in 16.1% and Philadelphia chromosome happened in 4%. The risk stratification was 39% SR, 32% IR, 29% HR. The induction remission rate was 96.7% and 3 died during induction. With a median follow up of 60 months (40-96), there were 50 relapses (34.2%): 33 in BM, 7 in CNS and 5 BM+CNS. Twenty patients received allogeneic haematopoietic stem cell transplant, 6 were transplanted in CR1 and the others were in second remission or beyond. Up to January 2001, 28 patients died, mostly due to relapse and 2 died of infection during remission. The 5-year overall survival for whole group, SR, IR and HR was 81.2%, 93.2%, 73.5% and 67.8% respectively. The 5-year event free survival for whole group, SR, IR, HR was 62.6%, 78.7%, 47.8% and 53.8% respectively.

Conclusion: The event free survival was inferior to other reported series, but salvage treatment after relapse could achieve a reasonable survival outcome.