Writing
A new systematic analysis of the International Agency for Research on Cancer (IARC), which is part of the World Health Organization (WHO), concludes that 17 genotypes Human papillomavirus (HPV) are responsible for invasive cervical cancer, with large differences in their carcinogenic strength.
It is study, published in The Lancetis based on a novel methodology that compares HPV genotypes in more than 110,000 women with cervical cancer with those of more than 2.5 million women without cancer (controls). Its objective was to evaluate which HPV genotypes caused cancer, as well as their carcinogenic potential and their contribution to the cervical cancer burden.
“This study constitutes the most comprehensive attempt to date to estimate the proportion of invasive cervical cancer.“
“This study represents the most comprehensive attempt to date to estimate the proportion of invasive cervical cancer caused by different HPV genotypes at global, regional and national levels.“, he says Gary Clifford, Deputy Head of the Early Detection, Prevention and Infections Branch at IARC and lead author of the paper.
“These findings directly inform strategies for the prevention of invasive cervical cancer, emphasizing targeted approaches through HPV vaccination and screening.“, he said.
Results
In the analysis, 17 HPV genotypes were considered to be causative of invasive cervical cancer, but with enormous differences in their carcinogenic strength. HPV types 16 and 18 caused approximately three-quarters of cervical cancer cases in all regions of the world. HPV types 31, 33, 45, 52 and 58 contributed to an additional 15–20% of cases.
“These data suggest that future HPV vaccines could focus on HPV 35 to reduce regional disparities.“
Furthermore, the remaining 10 causative genotypes caused only about 5% of cases worldwide, with some notable regional variations, including a higher proportion (4%) for HPV 35 in Africa than in other regions.
Specifically, the eight HPV genotypes with the highest attributable fractions (HPV types 16, 18, 31, 33, 35, 45, 52, and 58) were also the most carcinogenic. These genotypes are therefore clear priority targets for inclusion in HPV-based screening tests.
Other HPV genotypes, each of which causes only a small fraction of invasive cervical cancer cases, also have a lower positive predictive value. Including these genotypes in cervical cancer screening tests makes screening less effective and less cost-effective.
“Effective and equitable prevention of cervical cancer could be achieved by targeting at least the eight main HPV types in vaccines and diagnostics.”
“These data suggest that future HPV vaccines could focus on HPV 35 to reduce regional disparities.“says Dr. Clifford. In this regard, he insists that effective and equitable prevention of cervical cancer could be achieved “focusing on at least the eight major HPV types in vaccines and diagnostics, especially in resource-limited regions where the burden is greatest“.
Currently, in Spain, the Gardasil 9 vaccine helps prevent infection from the same 4 HPV types as Gardasil plus 5 other types of viruses considered high risk: 31, 33, 45, 52 and 58.
