title: Why does infection with some helminths cause cancer?
abstract: Infections withOpisthorchis viverrini, Clonorchis sinensisandSchistosoma haematobiumare classified as Group 1 biological carcinogens: definitive causes of cancer. These worms are metazoan eukaryotes, unlike the other Group 1 carcinogens including human papilloma virus, hepatitis C virus, andHelicobacter pylori. By contrast, infections with phylogenetic relatives of these helminths, also trematodes of the phylum Platyhelminthes and major human pathogens, are not carcinogenic. These inconsistencies prompt several questions, including how might these infections cause cancer? And why is infection with only a few helminth species carcinogenic? Here we present an interpretation of mechanisms contributing to the carcinogenicity of these helminth infections, including roles for catechol estrogen- and oxysterol-metabolites of parasite origin as initiators of carcinogenesis.
authors.affiliation: Department of Microbiology, Immunology and Tropical Medicine, and Research Center for Neglected Diseases of Poverty, School of Medicine & Health Sciences, George Washington University, Washington, DC 20037, USA.
authors.forename: Paul J
authors.initials: PJ
authors.lastname: Brindley
authors.affiliation: Center for Parasite Biology and Immunology, National Institute of Health Dr. Ricardo Jorge, Rua Alexandre Herculano, 321, 4000-055 Porto, Portugal; and Center for the Study of Animal Science, CECA/ICETA, University of Porto, Portugal.
authors.forename: José M Correia
authors.initials: JM
authors.lastname: da Costa
authors.affiliation: Tropical Disease Research Laboratory, Department of Pathology, and Liver Fluke and Cholangiocarcinoma Research Center, Faculty of Medicine, Khon Kaen University, Khon Kaen 40002, Thailand.
authors.forename: Banchob
authors.initials: B
authors.lastname: Sripa
keywords: Infection-related cancer; carcinogenesis; catechol estrogen quinone; cholangiocarcinoma; depurinating DNA adduct; helminth parasites; opisthorchiasis; oxysterol; squamous cell cancer of the bladder; urogenital schistosomiasis