HPV Types and Cancer Risk: A Critical Distinction
The HPV types that cause genital warts (types 6 and 11) are classified as low-risk and rarely cause cancer, while different HPV types (particularly 16 and 18) are responsible for the vast majority of HPV-related cancers. 1
Understanding HPV Type Classification
HPV types are categorized based on their cancer-causing potential:
Low-Risk HPV Types (Genital Warts)
- HPV types 6 and 11 cause approximately 90% of genital warts 1, 2, 3
- These low-risk types rarely are associated with invasive squamous cell carcinoma of the external genitalia 1
- They can cause benign conditions including genital warts, low-grade cervical lesions, and recurrent respiratory papillomatosis, but do not cause cervical or other HPV-related cancers 4
High-Risk HPV Types (Cancer-Causing)
- HPV types 16,18,31,33,35,39,45,51,52,56,58,59,68,69,73, and 82 are classified as high-risk carcinogens 1
- High-risk types are detected in 99% of cervical cancers, with types 16 and 18 alone causing approximately 70% of cervical cancers worldwide 1
- These same high-risk types cause vulvar, vaginal, penile, anal, and oropharyngeal cancers 1, 2
Critical Clinical Distinction
Genital warts themselves will not turn into cancer (except in very rare and unusual cases) 1. However, this does not mean a person is free from cancer risk:
- Patients with visible genital warts can be infected simultaneously with multiple HPV types, including both low-risk and high-risk types 1
- The presence of genital warts indicates HPV exposure but does not predict which other HPV types may be present 1
- No evidence indicates that either the presence of genital warts or their treatment is associated with the development of cervical cancer 1
Rare Exception: Low-Risk Types and Cancer
While HPV 6 and 11 are generally non-oncogenic, HPV types 16,18,31,33, and 35 are found occasionally in visible genital warts and have been associated with external genital squamous intraepithelial neoplasia 1. Recent evidence suggests that single or dual HPV6/11 infections have been found in variable proportions of penile (0-5.5%) and laryngeal cancers (0-87.5%), though other risk factors and co-carcinogens likely participate in these rare cases 5.
Essential Screening Implications
Women with genital warts should continue routine cervical cancer screening as recommended, not because the warts themselves cause cancer, but because they may have concurrent high-risk HPV infections 1. The screening detects precancerous changes from high-risk HPV types, which are separate from the low-risk types causing visible warts 1.
Vaccination Coverage
The quadrivalent HPV vaccine (Gardasil) protects against both:
- Low-risk types 6 and 11 (preventing 90% of genital warts) 3
- High-risk types 16 and 18 (preventing approximately 70% of cervical cancers) 1, 3
The newer 9-valent vaccine (Gardasil 9) extends protection to additional high-risk types (31,33,45,52,58), covering over 90% of HPV-related cancers 3.