The dual role of parasites and parasite-derived products in cancer biology: a systematic review of in vitro and in vivo evidence.

UNLABELLED: Parasites and parasite-derived molecules play a complex role in cancer biology, and growing evidence suggests they influence cancer development. This systematic review explores the mechanisms underlying the pro-tumour and anti-tumour effects of parasites and their molecules in experimental cancer models. A total of 34 studies were reviewed, covering whole parasites and parasite-derived molecules, including vesicles, peptides, proteins, and miRNAs, across different cancer types. The evidence shows that the effects of parasites and parasite-derived molecules on cancer depend strongly on the parasite species, the molecules involved, and the host response. Pro-tumour effects were mainly associated with chronic inflammation, oxidative stress, epithelial proliferation, and immune modulation. In contrast, anti-tumour effects were associated with direct cytotoxicity, inhibition of migration, and immune activation. Several parasite-derived molecules exhibited anti-tumour effects beyond their usual sites of infection, suggesting broader biological activity and potential therapeutic relevance. In conclusion, this review highlights the dual, context-dependent influence of parasites and parasite-derived molecules on cancer progression and supports further mechanistic and translational studies to investigate their potential as cancer-promoting factors and anticancer therapeutic candidates.

SYSTEMATIC REVIEW REGISTRATION: https://www.crd.york.ac.uk/PROSPERO/view/, identifier CRD420250656117.