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The International Agency for Research on Cancer (IARC) has evaluated the carcinogenicity of hepatitis D virus (HDV), human cytomegalovirus (HCMV), and Merkel cell polyomavirus (MCPyV). The outcome of the assessment has been published in a summary article in The Lancet Oncology.
HDV and MCPyV were previously evaluated by the IARC Monographs programme in Volumes 59 and 104, respectively. HCMV was evaluated for the first time.
HDV is an RNA virus, and the establishment of an HDV infection requires prior or simultaneous infection with hepatitis B virus. HCMV is a beta-herpesvirus that is transmitted through body fluids such as saliva, blood, urine, semen, and breast milk, and from mother to foetus during pregnancy. MCPyV is a polyomavirus that has a high prevalence in human populations; infections are typically acquired in early childhood via close contact, and the virus persists as a major component of the normal skin virome.
The Working Group evaluated HDV as carcinogenic to humans (Group 1) on the basis of sufficient evidence for cancer in humans. HDV causes hepatocellular carcinoma.
HCMV was classified as possibly carcinogenic to humans (Group 2B) on the basis of limited evidence for cancer in humans.
MCPyV was evaluated as carcinogenic to humans (Group 1) on the basis of sufficient evidence for cancer in humans and the combination of sufficient evidence for cancer in experimental animals and strong mechanistic evidence in exposed humans. MCPyV causes Merkel cell carcinoma.
The full scientific assessment will be published as Volume 139 of the IARC Monographs.
Karagas MR, Kaldor J, Michaelis M, Muchengeti MM, Alfaiate D, Argirion I, et al.
Carcinogenicity of hepatitis D virus, human cytomegalovirus, and Merkel cell polyomavirus
Lancet Oncol. Published online 27 June 2025;
https://doi.org/10.1016/S1470-2045(25)00403-6
