Does down syndrome affect the prognosis of acute lymphoblastic leukemia? A systematic review and meta-analysis

Down Syndrome (DS) is the most common human aneuploid abnormality. However, no association has been established between the presence of DS in Acute Lymphoblastic Leukemia (ALL) patients to affect survival rates. We searched in Medline, Scopus, and Web of Science databases for relevant studies. Binary outcomes were evaluated using risk ratios (RRs) with 95% confidence intervals (CIs). The risk of bias was performed using the Newcastle - Ottawa Scale (NOS). We included randomized controlled trials and cohort studies, with patients with newly diagnosed ALL and excluded studies with overlapping, reviews, animal model studies, or letters. All endpoints were analyzed using random-effect models. Heterogeneity was assessed using I2 statistics. Statistical analyses were performed using R, version 4.2.3. Sixteen studies, comprising 63,054 patients, were included. The outcomes demonstrated a significant difference favoring the ALL group for the outcomes as induction failure (RR 5.51 95% CI 3.50-8.69; p < 0.001); treatment-related mortality (RR 4.29 95% CI 3.38-5.45; p < 0.001), and total relapse (RR 1.28 95% CI 1.08-1.53; p = 0.004). There was no significant difference between the groups for event-free survival (5 years) groups (RR 0.91 95% CI 0.74-1.13; p = 0.40) and central nervous system relapse (RR 0.98 95% CI 0.55-1.72; p = 0.93). This meta-analysis found a significant difference when comparing the DS-ALL group with the ALL group, the results supported a higher risk of induction failure, treatment-related mortality, and total relapse in the DS-ALL group. The protocol was registered in the International Prospective Register of Systematic Reviews (PROSPERO), National Institute for Health and Care Research (NIHR), with registration number CRD5689342.