Li CK1, Luk CW2, Chan GCF3, Lee ACW4, Ling SC5, Ng MHL1, Chan LC3, Chik KW1, For the Hong Kong Paediatric Haematology & Oncology Study Group.

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


Objectives: To study the cytogenetic abnormalities of newly diagnosed ALL patients in Hong Kong Chinese children.

Method: All newly diagnosed ALL patients treated by 2 consecutive collaborative studies of Hong Kong Paediatric Haematology and Oncology Study Group were analysed for cytogenetic abnormalities of bone marrow. The response to treatment was compared among different groups of cytogenetic abnormalities.

Result: From 1993 to 2000, a total of 248 children were diagnosed ALL in Hong Kong. Nine cases did not have karyotyping performed (3.6% of all patients). Failure of karyotyping occurred in 41 cases (16.5% of all patients). Of the remaining 198 patients with positive yield, favourable cytogenetics with hyperdiploidy (chromosome > 50) was detected in 39 cases (19.7%). Unfavourable cytogenetics of Philadelphia chromosome, t(1;19) and t(4;11) occurred in 9 cases (4.5%), 8 cases (4%) and 4 cases (2%) respectively. Normal karyoptying (diploid) was found in 75 cases (37.9%) and 63 cases had other cytogenetic abnormalities (33.3%), these were grouped together as ‘other group’. Favourable cytogenetics had significantly less relapses as compared to unfavourable cytogenetics or ‘other group’ (15.4% vs 47.6% vs 23.5%, p=0.02). For patients with minimal follow up of one year, the 4 year overall survival of favourable, unfavourable and ‘other group’ was 94.4%, 50.8%, and 80% respectively (p=0.002); and 4 year event free survival for the 3 groups were 71%, 36.4% and 63.8% respectively (p=0.006).

Conclusion: The pattern of cytogenetic abnormalities in Chinese children with ALL was similar to those reported in Western countries, and the response to treatment was also comparable.