Increased Cadmium Load, Vitamin D Deficiency, and Elevated FGF23 Levels as Pathophysiological Factors Potentially Linked to the Onset of Acute Lymphoblastic Leukemia: A Review.

The preventability of acute lymphocytic leukemia during childhood is currently receiving great attention, as it is one of the most common cancers in children. Among the known risk factors so far are those affecting the development of gut microbiota, such as a short duration or absence of breastfeeding, cesarean section, a diet lacking in short-chain fatty acids (SCFAs), the use of antibiotics, absence of infection during infancy, and lack of pets, among other factors. Namely, it has been shown that iron deficiency anemia (IDA) and lack of vitamin D may cause intestinal dysbiosis, while at the same time, both increase the risk of hematological malignancies. The presence of IDA and vitamin D deficiency have been shown to lead to a decreased proportion of Firmicutes in stool, which could, as a consequence, lead to a deficit of butyrate. Moreover, children with IDA have increased blood concentrations of cadmium, which induces systemic inflammation and is linked to the onset of an inflammatory microenvironment in the bone marrow. Finally, IDA and Cd exposure increase fibroblast growth factor 23 (FGF23) blood levels, which in turn suppresses vitamin D synthesis. A lack of vitamin D has been associated with a higher risk of ALL onset. In brief, as presented in this review, there are three independent ways in which IDA increases the risk of acute lymphocytic leukemia (ALL) appearance. These are: intestinal dysbiosis, disruption of vitamin D synthesis, and an increased Cd load, which has been linked to systemic inflammation. All of the aforementioned factors could generate the appearance of a second mutation, such as ETV6/RUNX1 (TEL-AML), leading to mutation homozygosity and the onset of disease. ALL has been observed in both IDA and thalassemia. However, as IDA is the most common type of anemia and the majority of published data pertains to it, we will focus on IDA in this review.