Study 17 — Global Parasite-Attributable Cancer Burden and the Preventable Fraction: An Updated Integrated Estimate Using Population-Attributable Fraction Analysis Across Five Parasite–Cancer Pairs

Background. Chronic parasitic infections are Group 1 (IARC) carcinogens for at least three distinct cancers, yet no single published source has provided an updated, integrated estimate of current parasite-attributable cancer burden with an explicit preventable fraction analysis benchmarked to WHO control targets. This gap leaves parasite control programmes uncredited in global cancer prevention accounting. Methods. Population-attributable fraction (PAF) analysis using the Levin formula was applied to five parasite–cancer pairs: Schistosoma haematobium → bladder squamous cell carcinoma (SCC); Opisthorchis viverrini + Clonorchis sinensis → cholangiocarcinoma (CCA); Schistosoma japonicum → colorectal cancer (CRC); Plasmodium falciparum → endemic Burkitt lymphoma (eBL); and Strongyloides stercoralis / HTLV-1 co-infection → adult T-cell leukaemia/lymphoma (ATL). Exposure prevalence estimates were drawn from current WHO/IARC surveillance data; odds ratios from published meta-analyses. Preventable fractions were calculated at current intervention coverage and at WHO 50–80% coverage targets. Results. Across the five parasite–cancer pairs, current global parasite-attributable cancer...