Knowledge of the complexity of the gut microbiota is expanding, and its importance
in physiological processes and disease development is widely studied. The aim of this
review is to present the most relevant and recent research on the associations between
gut microbiota and oncologic disease. Recently, a number of associations between the
gut microbiome and neoplasms—regarding tumorigenesis, prognosis and therapeutic efficacy—have
been reported. The effects of the gut microbiome on these processes are via the direct
and indirect immunomodulating effects of bacteria. Studies have been done mainly in
adult populations, where its effect on immunomodulating therapies was unambiguous.
In paediatric populations, however, due to the low number of cases and the complex
therapeutic approaches, there have been only a few studies. Among them, children with
acute lymphoblastic leukaemia were mainly involved. Significant alterations in the
abundance of certain bacteria were associated with altered therapeutic responses.
Regarding solid tumours, studies with low case numbers have been reported; no significant
discoveries have been described so far. In the future, studies with larger cohorts
are needed in order to better understand the associations between bacteria and neoplasms
and to improve prognosis in the paediatric oncologic population.
