All risk factors
Every entry cites at least one primary source. Group 3 (not classifiable) and Group 4 (probably not carcinogenic) are hidden by default — toggle them in if you want the full IARC list.
- IARC Group 1Epstein-Barr virus (EBV)Infections
Infection. Spread through saliva; most adults are infected without symptoms. No vaccine yet.
- IARC Group 1Helicobacter pyloriInfections
Infection. Lives in the stomach lining of about half the global population; passes between people, often in childhood. Testable and treatable with antibiotics.
- IARC Group 1Hepatitis B virus (HBV)Infections
Infection. Spread through blood, sexual contact, and mother-to-child at birth. Risk is substantially reduced by HBV vaccination, recommended by WHO as part of routine childhood immunisation.
- IARC Group 1Hepatitis C virus (HCV)Infections
Infection. Spread through blood-to-blood contact (shared needles, historical transfusions). Curable with antiviral treatment.
- IARC Group 1Human papillomavirus (high-risk types)Infections
Infection. Spread through sexual contact; most adults are exposed at some point. Risk is substantially reduced by HPV vaccination given in adolescence under national immunisation programmes.
- IARC Group 1Human immunodeficiency virus (HIV-1)Infections
Infection. Spread through blood, sexual contact, and mother-to-child. Suppressible with antiretroviral therapy.
- IARC Group 1Human T-cell lymphotropic virus type 1 (HTLV-1)Infections
Infection. Spread through blood, sexual contact, and breastfeeding. Most common in Japan, the Caribbean, parts of Africa and South America.
- IARC Group 1Kaposi sarcoma-associated herpesvirus (KSHV / HHV-8)Infections
Infection. Spread mainly through saliva. Most people who carry it never develop disease; risk concentrates in people with weakened immune systems.
- IARC Group 1Merkel cell polyomavirus (MCPyV)Infections
Infection. Common skin virus most adults carry without symptoms.
- IARC Group 1Opisthorchis viverriniInfections
Infection. Caught from eating raw or undercooked freshwater fish in parts of Southeast Asia. Treatable with antiparasitic drugs.
- IARC Group 1Schistosoma haematobiumInfections
Infection. Caught from swimming or wading in contaminated fresh water in parts of Africa and the Middle East. Treatable with antiparasitic drugs.
- IARC Group 1Clonorchis sinensis (infection with)Infections
Classified by IARC as Group 1 — carcinogenic to humans. Strong evidence. (Vol 61, 100B, 2012)
- IARC Group 2BHuman immunodeficiency virus type 2 (infection with)Infections
Infection. Spread through blood, sexual contact, and mother-to-child. Less common worldwide than HIV-1.
- IARC Group 2BJC polyomavirus (JCV)Infections
Classified by IARC as Group 2B — possibly carcinogenic to humans. Evidence is limited. (Vol 104, 2014)
- IARC Group 2BSchistosoma japonicum (infection with)Infections
Classified by IARC as Group 2B — possibly carcinogenic to humans. Evidence is limited. (Vol 61, 1994)
- IARC Group 1Hepatitis D virusInfections
Classified by IARC as Group 1 — carcinogenic to humans. Strong evidence.