Pediatric cancer-associated thrombosis: Analysis from a tertiary care cancer center in India.

Background And Aims: Thrombotic events (TEs) have been extensively studied in adult cancer patients, but data in children are limited. We prospectively analyzed pediatric cancer-associated thrombosis (PCAT) in children with malignancies.

Methods: Children below 15 years of age with confirmed malignancies, treated at a large tertiary cancer center in India from July 2015 to March 2020 developing any TE were eligible. A standardized approach for detection and management was followed. Data were collected after informed consent.

Results: Of 6132 eligible children, 150 (2.44%) had 152 TEs, with median age 8.5 years and male:female of 1.83:1. Most TEs occurred on chemotherapy: 111 (74.0%). The most common site was central nervous system (CNS) 59 (39.3%), followed by upper-limb venous system 37 (24.7%). Hemato-lymphoid (HL) malignancies were more prone to PCAT than solid tumors (ST) (incidence 3.23% vs. 1.58%; odds ratio [OR] = 2.06, 95% confidence interval [CI] [1.36-2.88]; p < .001). Malignancies associated with PCAT were acute lymphoblastic leukemia (ALL) 2.94%, acute myeloid leukemia (AML) 6.66%, and non-Hodgkin lymphomas 5.35%. Response imaging done in 106 (70.7%) children showed complete to partial resolution in almost 90% children. Death was attributable to TE in seven (4.66%) children. Age above 10 years (OR 2.33, 95% CI [1.59-3.41]; p < .001), AML (OR 4.62, 95% CI [1.98-10.74]; p = .0062), and non-Hodgkin lymphoma (OR 4.01, 95% CI [1.15-14.04]; p = .029) were significantly associated with TEs. In ALL, age more than 10 years (OR 1.86, 95% CI [1.06-3.24]; p < .03), T-ALL (OR 3.32, 95% CI [1.69-6.54]; p = .001), and intermediate-risk group (OR 4.97, 95% CI [1.12-22.02]; p = .035) were significantly associated with thrombosis. The 2-year event-free survival (EFS) for HL malignancies with PCAT was 55.3% versus 72.1% in those without PCAT (p = .05), overall survival (OS) being 84.6% versus 80.0% (p = .32).

Conclusion: Incidence of PCAT was 2.4%, and occurred predominantly in older children with hematolymphoid malignancies early in treatment. Most resolved completely with low molecular weight heparin (LMWH) and mortality was low. In hematolymphoid malignancies, PCAT reduce EFS, highlighting the need for prevention.