Changes in the Prevalence of Oncogenic HPV Types

Recently, HPV prevalence has decreased dramatically in the USA (Markowitz LE, Pediatrics, 2019). Surprisingly, the nonavalent vaccine optimally decreased the prevalence of the most common, high-risk HPV types and also reduced the incidence of premalignant cervical lesions (Mariani L, Int J Gynaecol Obstet, 2017). The data thus suggest that both the bivalent and quadrivalent HPV vaccines eliminate HPV16- and 18-associated cervical cancers.

Regrettably, in Japan, use of the bivalent and quadrivalent prophylactic HPV vaccines almost ceased, by government decree, in June 2013 (Hanley JBS, Lancet, 2015). However, about 70% of girls aged 13-18 years were immunized with these vaccines during 2010-2012. A small decrease in cervical intraepithelial neoplasia grade 3 (CIN3) has been observed in 20-year-old Japanese women who underwent HPV vaccination (Yagi A, Vaccine, 2019).The investigators recently found nationwide (unpublished) data suggesting that the incidence of condyloma has decreased in Japanese women aged in their early twenties, but has apparently increased in males. The decrease in women may be attributable to quadrivalent HPV vaccination, which protects against HPV6 and 11 infections. Further work is necessary, as statistical analysis is lacking, and the proportion of quadrivalent vaccinations among all vaccinations is unknown in Japan.

The investigators earlier reported a high prevalence of HPV infection and associated cervical abnormalities in 6,628 women aged 16-50 years. The work was performed from October 2011 to March 2012 and was reported in JHERS-2016 (Sasagawa T, J Med Virol, 2016). The investigators recorded demographic information including age, marital status, any history of or current sexually transmitted disease (STD), any cervical abnormalities, and any other gynecological problems. HPV genotyping (31 types) and the Pap test were performed for all subjects. This is the only study that has investigated HPV prevalence and cervical SILs in the general population. The information collected included sexual details and any history of HPV vaccination. Routine gynecological examination, the Pap test (employing liquid-based cytology [LBC]), and HPV genotyping of LBC samples were performed. These data allow us to compare the status of women in the vaccine and (present) no-vaccine era.

It is possible to essentially eliminate cervical cancer by implementation of nanovalent HPV vaccination and careful cancer screening (HPV testing). However, some specialists suggest that reductions in certain HPV types might induce increases in other HPV types that are not targeted by vaccination and not tested during cancer screening. Not only the existing 13 high-risk HPV types but also other HPV types considered to probably or possibly associated with high risk are found in some cervical cancer tissues (Halec G, J Pathology 2014). The investigators also found such HPV types in high-grade SILs, as reported in JHERS-2016 (Sasagawa T, J Med Virol, 2016) and a recent publication (Sakamoto J, Papillomavirus Res, 2019). Therefore, in the present project, the investigators will document the prevalence of all oncogenic HPV types, including the 13 recognized high-risk types and the probable high-risk types (HPV26, 30, 34, 53, 66, 67, 69, 70, 73, 82, and 85).