Learning Objectives
Master the Oncogenic Microbes that drive human malignancy. Understand how viruses, bacteria, and parasites—ranging from HPV to H. pylori—reprogram host cells or create chronic inflammatory environments that lead to specific cancers.
1. DNA & RNA Viruses
Oncogenic viruses often integrate into the host genome or produce proteins that inhibit tumor suppressor genes (like p53 and Rb), leading to unregulated cell cycles.
| Microbe | Associated Cancer(s) | Clinical Context |
|---|---|---|
| EBV | Burkitt lymphoma, Hodgkin lymphoma, Nasopharyngeal carcinoma. | Also causes 1° CNS lymphoma in immunocompromised patients. |
| HPV (16, 18) | Cervical, penile/anal carcinoma, Head and neck cancer. | E6 inhibits p53; E7 inhibits Rb. |
| HBV / HCV | Hepatocellular carcinoma (HCC). | Chronic inflammation and regeneration. |
| HHV-8 | Kaposi sarcoma. | Classically seen in HIV/AIDS patients. |
| HTLV-1 | Adult T-cell Leukemia/Lymphoma. | A retrovirus affecting T-lymphocytes. |
2. Bacterial & Parasitic Oncogenesis
Chronic infection with certain bacteria or parasites causes persistent tissue damage and inflammation, which significantly increases the risk of specific organ-based cancers.
| Microbe | Associated Cancer | Mechanism Note |
|---|---|---|
| H. pylori | Gastric adenocarcinoma and MALT lymphoma. | Chronic gastritis leads to intestinal metaplasia. |
| Clonorchis sinensis | Cholangiocarcinoma. | Liver fluke infecting the bile ducts. |
| Schistosoma haematobium | Squamous cell bladder cancer. | Chronic bladder irritation by parasite eggs. |
Activity:
Activity
High-Yield Mnemonics & Tips:
- Kaposi Mnemonic: Think of HHV-8 for Ka-8-si Sarcoma.
- Bladder Cancer Distinction: Tobacco smoke causes Transitional cell carcinoma, but Schistosoma causes Squamous cell carcinoma.
- HPV Proteins: Remember 6 inhibits 53 (E6 inhibits p53) and 7 inhibits Rb (E7 inhibits Rb). 6 comes before 7, and p53 is often considered the more “primary” suppressor.