Acute lymphoblastic leukemia in first complete remission: temporal trend of outcomes in studies comparing allogeneic transplant with autologous transplant or chemotherapy.

In patients with acute lymphoblastic leukemia in first complete remission, several studies have compared allogeneic transplant with autologous transplant or chemotherapy. This material can be the basis for analyzing the temporal trend of outcomes. Our study was designed as a meta-regression focused on temporal trends and based on the endpoint of 5-year leukemia-free survival (5yLFS). Studies in which 5yLFS was determined in a patient group subjected to allogeneic transplant and in a control group (treated with autologous transplant and/or chemotherapy) were eligible for our meta-analysis. A standard literature search was carried out to identify pertinent studies. The results of included studies were submitted to an observational meta-analysis and to a meta-regression focused on two covariates (calendar year in which the study was conducted; percentage of high-risk patients). The endpoint of 5yLFS was separately assessed between allogeneic transplant and autologous transplant or chemotherapy. Our analysis included 14 studies that covered a period (1983 to 1999) in which patients were conditioned only with myeloablative conditioning and not with non-myeloablative ones. In the risk ratio (RR) analysis, the pooled outcome showed a significantly better profile for allogeneic transplantation (RR = 1.42; 95 % confidence interval (CI), 1.22 to 1.65). Separate analysis of the two treatment options found a pooled 5yLFS of 45 % (95 % CI, 38 to 51 %) for allogeneic transplant vs 30 % (95 % CI, 23 to 37 %) for the controls. In meta-regression, the temporal trend analysis revealed that, in patients subjected to allogeneic transplant, the values of 5yLFS showed no significant change over the 16-year interval (p = 0.720); the same stability over time was found in the control group (p = 0.489). On the other hand, the percentage of high-risk patients influenced outcomes in both patient groups at levels of statistical significance (p = 0.014 and p = 0.045 in the allotransplant group and in the controls, respectively). Our results can represent a reference point for future analyses focused on patients treated in more recent years.