New strategies for standardised and appropriate access to a complete acute lymphocytic leukaemia diagnostic panel for children in Mexico: an observational study

Abstract

Background

Approximately 50% of all childhood cancer cases in Mexico are acute lymphocytic leukaemia. Survival rates are suboptimal when compared with those in high-income countries, and poor access to standardised testing and treatment has been identified as a contributing factor. Mexico in Alliance with St Jude (MAS) is a multisite intersectoral collaboration created in 2016 to improve childhood cancer outcomes. MAS conducted a retrospective analysis of childhood acute lymphocytic leukaemia where diagnostic disparities and risk-group classification emerged as a challenge; 419 (72%) of 578 of patients with confirmed acute lymphocytic leukaemia did not have access supporting fluorescent in-situ hybridisation (FISH) testing and 226 (39%) of 578 patients did not have minimal residual disease evaluation. FISH results were reported in a median of 15 days (SD 17) and cytogenetic results were reported after a median of 22 days (SD 27). In response, MAS launched The Bridge Project, in 2019, to improve access, accuracy, and timeliness of diagnostic information for children with acute lymphocytic leukaemia in Mexico.

Methods

A consensus-derived standardised diagnostic panel for children aged 0–18 years with suspected acute lymphocytic leukaemia was developed, including morphology, immunophenotype, karyotype, FISH, DNA index, and minimal residual disease evaluation at two timepoints: day 15 and after consolidation. Participating centres shipped diagnostic samples to a single central laboratory. Paediatric oncologists, nurses, clinical research coordinators, and laboratory technicians held weekly meetings for quality improvement.

Findings

The Bridge Project has benefited 255 children by providing consistent access to a comprehensive diagnostic panel. 556 (94%) of 591 samples arrived within the target timeframe (≤48 h). Immunophenotype, karyotype, DNA index, FISH, and minimal residual disease access increased from 97%, 76%, 77%, 28%, and 61%, respectively, to 100%. The single central laboratory produced flow cytometry results (immunophenotype and minimal residual disease) and FISH results within 5 days and karyotype results within 13 days of sample arrival. Many structural and logistical challenges were successfully addressed through multidisciplinary and intersectoral collaboration. Eleven additional institutions joined the project in 2022, up from five in 2021.

Interpretation

Timely access to standard specialised diagnostic testing for children with suspected acute lymphocytic leukaemia following a centralised approach is possible in lower-resource settings through multisite intersectoral collaboration. This synergistic action is benefiting children by providing timely access to a comprehensive diagnostic panel and serves as an example of health system resilience.

Funding

Fundación Gonzalo Río Arronte (Mexico City, Mexico); Casa de la Amistad para niños con Cáncer (Mexico City, Mexico); St Jude Children's Research Hospital (Memphis, TN, USA).