Long-Term Follow-Up of Treatment Outcome and Prognosis in 96 Chinese Children with Acute Myeloid Leukemia: A Single Center Experience.

Owing to the intensification of chemotherapy, the complete remission (CR), overall survival (OS), disease free survival (DFS) and event free survival (EFS) rates in childhood AML have been significantly improved during the past two decades in western countries. However, reports on the long-term outcome of this disease in Chinese children remain to be very limited. Objectives The aims of this study were to investigate the outcome and prognostic factors in Chinese childhood AML treated in our hospital during the past 7 years and to provide the basis for further improvement of outcome in children with AML. Methods From April 1998 to August 2005, 96 children (51 boys and 45 girls, aged 1.5 ~ 16.1 yrs with a median age of 9) with de novo AML diagnosed in our hospital based on MICM criteria were enrolled into this study. In total, 57 patients with non-APL AML were treated with the induction therapy of daunorubicin (maximum total cumulative dose 360 mg/M²) + Ara-C (DA) or homoharringtonine + Ara-C (HA), post-remission therapy with high-dose (1~2 g/M² q12h for 6 doses) Ara-C containing regimens for three-month courses, and low-dose therapy with daunorubicin, homoharringtonine, etoposide (maximum total cumulative dose 1800 mg/M²) and Ara-C for three-month courses, followed by maintenance therapy for a total of 2~2.5 yrs. The 39 patients with APL were treated with all-trans retinoic acid (ATRA) and drugs above. Results Out of 96 patients, 86 children (89.6%) achieved CR. The estimated OS rates at three, five and seven years were (67.2±5.5)%, (58.1±6.4)% and (49.6±8.0)%, respectively, while the EFS rates were (52.3±5.8)%, (47.6±6.2)% and (47.6±6.2)%, and the DFS rates were (55.9±6.0)%, (50.7±6.4)% and (50.7±6.4)%, respectively. Univariant analysis showed that the variables predicted higher CR rates included the WBC counts (93.2% for patients < 100 × 10⁹/L vs 50.0% for those ≥ 100 × 10⁹/L, P = 0.004) at diagnosis, and the blasts (100% for patients without blasts vs 85.2% for those with blasts, P = 0.023) in the peripheral blood. The variables predicted longer survival duration included WBC counts ((49.1±6.5)% of 5yr EFS for patients < 100 × 10⁹/L vs (33.3±18.0)% for those ≥ 100 × 10⁹/L, P = 0.022) at diagnosis, FAB subtypes ((55.9±9.7)% for M3 vs (40.4±7.7)% for non-M3, P =0.048), course numbers [(76.0±12.2)% of 5-yr ESF for 1 course vs (31.1±9.0)% for more than 2 courses, P = 0.026) for achieving CR, CD38+ ((57.9± 7.3)% for CD38+ vs (16.7%± 10.8)% for CD38−, P = 0.005), CD14− ((49.9± 7.3)% for CD14− vs (21.5%± 14.2)% for CD14+, P = 0.001), CD34− ((54.7± 9.7)% for CD34− vs (32.6%± 8.8)% for CD34+, P = 0.038) and HLA-DR- ((57.7± 17.7)% for HLA-DR- vs (39.9%± 7.4)% for HLA-DR+, P = 0.024). 17 patients lost follow-up. The total cumulative relapse rate was 31.6% (25/79) with all BM relapse. The total treatment related modality rate was 5.3%. No secondary malignancy case was identified. Conclusions DA-based induction and high dose Ara-C-based post-remission treatment are effective to improve the CR rate and long-term survival in Chinese children with AML. The results are comparable to those reported in western countries. Initial WBC counts, early response to chemotherapy, FAB subtypes and some immunological markers are proved to be the significant prognostic factors for childhood AML under our current protocol.