Oncogenic viruses and H. pylori: the table to know !
- Topic
Some viruses, one bacterium and a few parasites can cause cancer, either by switching off the cell's brakes or by keeping tissue inflamed for years.
Updated 2026-11-01
What it is
Infections cause a large share of cancers worldwide, especially in low- and middle-income countries such as Colombia. Some agents act directly, with viral proteins that block tumour suppressors (HPV) or mimic growth signals (EBV, HTLV-1, HHV-8); others act indirectly, through years of chronic inflammation and cell turnover (hepatitis B and C, H. pylori, flukes). Many of these cancers are preventable by vaccination, treatment of the infection or screening.
Key facts
- HPV integration usually breaks the viral E2 gene, which then no longer restrains E6 and E7 expression.
- Burkitt lymphoma carries the MYC translocation t(8;14); endemic African cases are EBV-associated.
- Early gastric MALT lymphoma can regress after H. pylori eradication.
- HIV itself is not oncogenic; it raises cancer risk through immunosuppression.
Step by step
- Direct route: the viral genome persists in the cell, often integrated into host DNA (HPV, HBV).
- Viral oncoproteins disable tumour suppressors (p53, RB) or switch on growth pathways (NF-κB).
- Indirect route: the agent keeps the tissue inflamed for years (HCV, H. pylori, flukes).
- Inflammation produces free radicals and forces constant regeneration, so replication errors accumulate.
- Immunosuppression (HIV, transplant) lets virus-driven clones escape (Kaposi sarcoma, EBV lymphomas).
- Only a minority of infected people develop cancer, after a long latency and with cofactors.
Infectious agents and the cancers they cause
| Agent | Cancer | Key mechanism |
|---|---|---|
| High-risk HPV (types 16, 18 and others) | Cervical, anal, oropharyngeal, vulvar, vaginal and penile carcinoma | E6 degrades p53; E7 binds and inactivates RB |
| Hepatitis B virus | Hepatocellular carcinoma | Chronic inflammation and regeneration; DNA integration; HBx protein |
| Hepatitis C virus | Hepatocellular carcinoma (and some B-cell lymphomas) | Chronic inflammation and cirrhosis (an RNA virus that does not integrate) |
| Epstein–Barr virus | Burkitt lymphoma, Hodgkin lymphoma, nasopharyngeal carcinoma, lymphomas in immunosuppression | LMP1 mimics a growth signal (NF-κB); B-cell proliferation |
| HHV-8 (KSHV) | Kaposi sarcoma, primary effusion lymphoma | Viral cyclin and anti-apoptotic proteins; mostly with immunosuppression |
| HTLV-1 | Adult T-cell leukaemia/lymphoma | Tax protein activates host growth genes and NF-κB |
| Merkel cell polyomavirus | Merkel cell carcinoma | Viral T antigens inactivate RB |
| Helicobacter pylori | Gastric adenocarcinoma and gastric MALT lymphoma | Chronic gastritis, atrophy, intestinal metaplasia; CagA |
| Schistosoma haematobium | Squamous cell carcinoma of the bladder | Chronic inflammation around eggs in the bladder wall |
| Liver flukes (Clonorchis, Opisthorchis) | Cholangiocarcinoma | Chronic inflammation of the bile ducts |
Clinical notes
- Colombia and Latin America: H. pylori infection is very common, and gastric cancer is a leading cause of cancer death, highest in the Andean regions.
- The Correa cascade (gastritis → atrophy → intestinal metaplasia → dysplasia → carcinoma) was described from studies in Nariño, Colombia.
- Cervical cancer is largely preventable: HPV vaccination before sexual debut and screening (HPV testing, cytology).
- Hepatitis B vaccination of newborns is cancer prevention; HTLV-1 is endemic in some areas, including the Colombian Pacific coast.
Test yourself
Think of the answer, then tap the question to see it.
How do the HPV proteins E6 and E7 promote cancer?
E6 marks p53 for degradation and E7 binds RB, releasing E2F; the cell loses both its guardian and its cell-cycle brake.
Which cancers are linked to Epstein–Barr virus?
Burkitt lymphoma, many Hodgkin lymphomas, nasopharyngeal carcinoma and lymphomas in immunosuppressed patients.
Which tumour can regress after H. pylori eradication?
Early gastric MALT lymphoma.
Which parasite is linked to squamous cell carcinoma of the bladder?
Schistosoma haematobium, through chronic inflammation around its eggs.
How does HIV increase cancer risk if it is not itself oncogenic?
By depleting CD4 cells and weakening immune surveillance, so oncogenic viruses such as HHV-8, EBV and HPV act unchecked.
Related
- Tumour suppressor genes: RB, TP53, APC, BRCA and the two-hit hypothesis
- Oncogenes: RAS, MYC, HER2, BCR-ABL and the table to know
- Precancerous conditions: when chronic inflammation, metaplasia or hyperplasia raise the risk
- Chronic inflammation: causes, cells and features
- Cancer epidemiology: age, environment, predisposing conditions (and Colombia)
- How tumours evade the immune system
- Dysplasia and carcinoma in situ
- Multistep carcinogenesis: the adenoma–carcinoma sequence
Related conditions
- Cervical cancer
- Cervical intraepithelial neoplasia (cervical dysplasia)
- Human papillomavirus (HPV) infection
- Anal cancer
- Head and neck squamous cell carcinoma (oral cavity and oropharynx, HPV)
- Hepatocellular carcinoma
- Viral hepatitis
- Kaposi sarcoma
- Nasopharyngeal carcinoma
- Hodgkin lymphoma
- Non-Hodgkin lymphoma
- Gastric cancer
- Helicobacter pylori gastritis
- Merkel cell carcinoma
- Cholangiocarcinoma (bile duct cancer)
- Schistosomiasis
- Liver fluke infections (fascioliasis, clonorchiasis, opisthorchiasis)
- HIV infection and AIDS
- HTLV-1-associated myelopathy / tropical spastic paraparesis
Elsewhere in DurgiPedia
- Oncogenes and tumour suppressor genes
- Tumor immunology and checkpoint inhibitors
- Cervix and vagina: the transformation zone
Microorganisms
- Human papillomavirus
- Epstein–Barr virus
- Hepatitis B virus
- Hepatitis C virus
- Human herpesvirus 8
- Human T-lymphotropic virus type 1
- Helicobacter pylori
- Schistosoma mansoni / S. haematobium / S. japonicum
- Clonorchis sinensis / Opisthorchis spp.
- Human immunodeficiency virus
Educational content on the mechanisms of disease; not a diagnostic or treatment guide and no substitute for a health professional's advice. No doses are given.
Sources: Infectious Agents (National Cancer Institute (NCI), 2026); Human Papillomavirus (StatPearls (NCBI Bookshelf), 2024); Helicobacter Pylori (StatPearls (NCBI Bookshelf), 2024); Cancer (World Health Organization (WHO), 2026).
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Representative model, for educational purposes only.