Therapeutic effectiveness of the ALL-XH-99 protocol for childhood acute lymphoblastic leukemia.

Objective: The ALL-XH-99 protocol for the treatment of childhood acute lymphoblastic leukemia (ALL) has been performed in the Union Hospital for 10 years. This study aimed to evaluate the therapeutic effectiveness of the protocol for childhood ALL and to investigate the prognostic factors for childhood ALL.

Methods: This is a retrospective study. The eligible patients were treated with the ALL-XH-99 protocol. However a minor modification based on the ALL-XH-99 protocol was performed in this study, i.e., the high-risk patients as the low- and moderate-risk patients were not administered with cranial irradiation. Event-free survival (EFS) was evaluated using the Kaplan-Meier method and the differences of the EFS among groups were compared with the log-rank test. Prognostic factors for childhood ALL were investigated by the stepwise Cox proportional hazard model.

Results: One hundred fifteen patients were eligible for the ALL-XH-99 protocol clinical study. The 115 patients consisted of 62 low-risk, 12 moderate-risk and 41 high-risk patients. The overall EFS at 5 years in the 115 patients was 69.0 +/- 5.0%. The 5-year-EFS in the low-risk, moderate-risk and high-risk patients was 82.0 +/- 6.0%, 77.0 +/- 15.0% and 43.0 +/- 11.0%, respectively (P <0.01). Relapse occurred in 16 patients (13.9%) in a median time of 17 months. Without administering cranial irradiation to all of the patients, the incidence of CNS leukemia relapse (2/115, 1.7%) was not higher than that previously reported. Multivariate analysis showed that the risk degree of leukemia, the presence of t (9; 22)/bcr/abl fusion gene and leukocyte count were independent adverse prognostic factors for ALL and their hazard ratio was 1.867, 3.397 and 2.236 respectively.

Conclusions: The therapeutic effectiveness of the ALL-XH-99 protocol for childhood ALL is satisfactory, with an EFS rate comparable to that of the developed countries. t (9; 22)/bcr/abl is the most important adverse independent prognostic factor for childhood ALL. Cranial irradiation may be eliminated to reduce late adverse effects in all of ALL patients.