Are 20 human papillomavirus types causing cervical cancer?

Area of Science:

• Oncology
• Virology
• Epidemiology

Background:

• The International Agency for Research on Cancer (IARC) classified 12 human papillomavirus (HPV) types as Group 1 carcinogens for cervical cancer in 2012.
• These Group 1 HPV types belong to the α-Papillomaviridae family, specifically species α5, α6, α7, and α9.
• HPV68 is classified as a Group 2A carcinogen (probably carcinogenic), and seven other HPV types are Group 2B carcinogens (possibly carcinogenic).

Purpose of the Study:

• To review the carcinogenicity classification of HPV types in relation to cervical cancer.
• To evaluate the contribution of less common HPV types to cervical cancer burden.
• To assess the potential need for reclassification of certain HPV types based on recent evidence.

Main Methods:

• Review of epidemiological, experimental, and mechanistic evidence for HPV carcinogenicity.
• Analysis of molecular signatures in HPV-induced cervical cancers.
• Examination of meta-analyses on HPV prevalence in cervical cancer versus normal cytology.

Main Results:

• Ninety-six percent of cervical cancers are attributed to 13 common HPV types (Groups 1 and 2A).
• Including seven Group 2B HPV types increases the attributable percentage to 98.7%.
• Recent meta-analyses suggest some Group 2B HPV types (e.g., HPV68, HPV26, HPV66) are more prevalent in cancer cases, potentially warranting reclassification.

Conclusions:

• The majority of cervical cancers are caused by a limited number of high-risk HPV types.
• While some rarer HPV types show associations with cervical cancer, their overall contribution is small.
• Reclassification of certain HPV types may be considered, but their rarity limits the need for inclusion in current screening or vaccination strategies.