Beneficial effects of human papillomavirus vaccine for prevention of cervical abnormalities in Miyagi, Japan

Abstract

Prevention of cervical cancer has been unsuccessful in Japan because of low rates of cancer screening and vaccination. The Vaccine Adverse Review Committee of the Japanese Government investigated 2,475 adverse events and reported 617 (6.9/100,000) severe cases and 176 (2.0/100,000) cases with chronic pain. The proactive recommendation for human papillomavirus (HPV) vaccination has been suspended since June 2013. In this study, we examined vaccination rate and incidence of abnormal cervical cytology in women aged 20 to 24 years attending cancer screening in Miyagi. Among the 3,272 women who underwent a health check in the fiscal year 2014 (April 2014-March 2015), 332 (10.2%) received a HPV vaccination. The HPV vaccination rates were 42.3%, 10%, 17.5%, 3.8% and 4.0% in women aged 20, 21, 22, 23 and 24 years, respectively. The rates of atypical squamous cells of undetermined significance (ASC-US) or worse were 2.41% (8/332) in women with HPV vaccination and 5.03% (148/2,940) in those without HPV vaccination, indicating a significant decrease in vaccinated women (p = 0.03). ASC-US cases were referred to HPV DNA tests. In addition, the rates of high grade squamous intraepithelial lesion (HSIL) or worse were 0.30% (1/332) in women with HPV vaccination and 0.82% (24/2,940) in those without HPV vaccination, showing the marginal decrease in women who were vaccinated (p = 0.3). Thus, this study indicates that HPV vaccination is associated with a reduction in the incidence of cervical abnormalities, suggesting a need for scientific discussion of reinstatement of proactive recommendation for HPV vaccine in Japan.