Childhood acute lymphoblastic leukemia survival and spatial analysis of socio-environmental risks in Mexico

Jaqueline Calderon-Hernandez, Lizet Jarquin-Yañez, Luis Reyes-Arreguin, Luis A. Diaz-Padilla, Jose Luis Gonzalez-Compean, Pablo Gonzalez-Montalvo, Rebeca Rivera-Gomez, Jairo R. Villanueva-Toledo, Kristal Pech, Oscar Arrieta and Yelda A. Leal.

Introduction

Childhood and adolescent cancer is a significant and relevant public health challenge; each year, an estimated 400,000 children <19 years old are diagnosed with cancer globally. Ninety percent of them live in low- and middle-income countries (LMICs) where treatment is often unavailable or unaffordable. As a result, less than 30% of children with cancer in LMICs survive, compared to more than 80% of those in high-income countries (HICs) (1, 2). The World Health Organization (WHO) Global Initiative on Childhood Cancer proposes reaching at least a 60% cancer survival rate, thereby saving one million lives of children with cancer by 2030 (3). The Global Initiative for Childhood Cancer is part of the response to the World Health Assembly resolution Cancer Prevention and Control through an Integrated Approach, focused on the reduction of premature mortality from non-communicable diseases (NCDs) and the achievement of universal health coverage (4).

Leukemia is the most frequently occurring cancer among children and adolescents; acute lymphoblastic leukemia (ALL) is the most common type, and over 80% of ALL cases are classified as B-lineage (B-ALL). ALL is characterized by the rapid proliferation of poorly differentiated progenitor cells inside the bone marrow (5, 6). Leukemia, among other health conditions, has been included in the group of “new pediatric conditions” (7). Some chemical toxicants in the environment are known and suspected causal factors of the disease (8, 9). It is estimated that 17% (7% to 42%) of all cancer disease burdens in children under five can be attributable to environmental causes; in today’s world, children are surrounded by an estimated 350,000 chemicals (10, 11).

Although the ALL etiology in children and adolescents remains largely unknown, evidence suggests exposure to ionizing radiation, albeit rare, and prenatal/postnatal exposures to pesticides are linked to an increased risk of ALL (12–14). In addition, certain behaviors, such as pica (placing hands and objects in one’s mouth) and playing outside, increase children’s odds of exposure (4). Regarding exposures in urban environments, residential proximity to petrol stations and industrial sites and exposure to mixtures of benzene, particulate matter ≤2.5 µm (PM_2.5), and polycyclic aromatic hydrocarbons (PAHs) from traffic emission are related to high risk of ALL (15–18).

Interpretation of epidemiologic evidence to determine causality is complex and relies on a wide range of supporting data. The study of cancer and environmental exposures often involves collecting and studying large, complex datasets of cases, environmental exposure patterns or biological indexes, and additional variables (19). In the absence of desirable data on cancer cases from population-based cancer registries (PBCRs), hospital-based cancer registries (HBCRs) could be an alternative.

For this reason, the WHO, through the Global Initiative for Cancer Registry (GICR; www.gicr.iarc.fr) and the International Agency for Research on Cancer (IARC), has promoted establishing cancer registry and surveillance strategies, with standards and quality procedures to provide reliable and better data regarding cancer burden and setting priorities for cancer control and prevention, especially in LMICs.

Therefore, to increase our knowledge and awareness of environmental factors and ALL in Mexican children <19 years old, we designed this research to compare ALL survival rates in four contrasting urban areas (northern, central, and southern). Also, we present an overview analyzing the distribution of the disease from a territorial perspective aiming to identify ALL clusters, visualize areas vulnerable to the disease, and characterize fixed small-scale carcinogens hotbeds at the local/neighborhood level.

https://doi.org/10.3389/fonc.2023.1236942