## HPV Types and Cervical Carcinoma Risk **High-Yield:** HPV 16 and 18 are the two most oncogenic types, responsible for approximately 70% of all cervical cancers worldwide. ### Classification of HPV Types | HPV Type | Risk Category | Associated Lesion | Cancer Risk | |----------|---------------|-------------------|-------------| | 16, 18 | High-risk (HR) | CIN 2/3, invasive cancer | Very high (~70% of cases) | | 31, 33, 35, 39, 45, 51, 52, 56, 58, 59, 66, 68 | High-risk (HR) | CIN 2/3, invasive cancer | High (~25% of cases) | | 6, 11 | Low-risk (LR) | Condyloma acuminatum, CIN 1 | Very low (<1%) | | 1, 2, 3, 4, 5, 7, 10 | Low-risk (LR) | Benign warts | Negligible | ### Key Pathogenic Features **Key Point:** HPV 16 and 18 encode viral oncoproteins E6 and E7 that: 1. E6 protein inactivates p53 (tumor suppressor) 2. E7 protein inactivates Rb (retinoblastoma protein) 3. Together they promote uncontrolled cell proliferation and genomic instability **Clinical Pearl:** HPV 18 is associated with adenocarcinoma of the cervix, while HPV 16 is more commonly linked to squamous cell carcinoma, though both can cause either histological type. **Mnemonic:** **HR-HPV (High-Risk)** — Remember **16 & 18 are the "terrible twins"** for cervical cancer risk; all others are either low-risk or intermediate-risk. [cite:Robbins 10e Ch 22]
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