Parasitic Infections, Antiparasitic Treatment, and the Global Burden of Infection-Associated Cancers: A Systematic Review and Meta-Analysis

Parasitic infections remain highly prevalent in many low- and middle-income countries and represent an underrecognized contributor to infection-associated cancers. Certain helminths have been classified as definite human carcinogens, yet the magnitude of their impact on global cancer burden and the potential preventive role of antiparasitic interventions remain incompletely defined. This systematic review and meta-analysis synthesized epidemiological evidence linking parasitic infections to cancer and evaluated the effect of control strategies on long-term cancer risk. A comprehensive search of major databases from inception to December 2025 identified observational and interventional studies reporting associations between parasitic infections and malignancy. Random-effects meta-analysis was conducted for parasite–cancer pairs with sufficient comparable data. Sixty-eight studies met inclusion criteria, and thirty-nine were included in quantitative synthesis. Infection with Schistosoma haematobium was associated with a significantly increased risk of bladder cancer (pooled OR 2.18; 95% CI 1.72–2.76), while liver fluke infections (Opisthorchis viverrini and Clonorchis sinensis) were strongly associated with cholangiocarcinoma (pooled OR 4.12; 95% CI 3.01–5.64). Heterogeneity across studies was moderate to high but did not materially alter overall conclusions in sensitivity analyses. Ecological and observational evidence suggests that sustained antiparasitic mass drug administration programs may contribute to reductions in infection-associated cancer burden, although high-quality longitudinal data are limited due to long latency periods. These findings underscore the substantial oncologic consequences of chronic parasitic infections and support integration of parasite control into broader cancer prevention strategies, particularly in endemic regions