麻豆传媒

England's human papillomavirus (HPV) vaccination program has remained highly effective in reducing cases of cervical cancer and grade 3 cervical intraepithelial neoplasia (CIN3) across socioeconomic deprivation groups, according to an observational study.

In a birth cohort of women offered HPV vaccination routinely at ages 12-13 years, the adjusted age-standardized incidence rates of cervical cancer and CIN3 over the additional 12 months of follow-up were 83.9% and 94.3% lower than in the reference cohort of women who were never offered HPV vaccination, reported Peter Sasieni, PhD, of Queen Mary University of London, and colleagues in .

The highest incidence rates for invasive cervical cancer remained among women living in the most deprived areas, but the authors noted that the HPV vaccination program had a large effect in all five deprivation levels.

"HPV vaccination really does work in preventing cervical cancer, but to be highly effective at a population level, it is vitally important to achieve high coverage in all sectors of society," Sasieni told 麻豆传媒. "That is not easy, but it is possible, as has been demonstrated with the HPV immunization program in England."

"The success of HPV immunization in England should encourage us all to redouble efforts to ensure high HPV vaccination coverage throughout the world," he added. "The burden of cervical cancer falls most heavily on low- and middle-income countries. We cannot leave them behind."

In , Kalyani Sonawane, PhD, of the MUSC Hollings Cancer Center in Charleston, South Carolina, and colleagues noted that "the human and monetary consequences of cervical cancer and treatment averted through HPV vaccination outweigh the costs of making it accessible to all age-eligible individuals."

The findings of the study suggest that "marginalized groups may benefit from the HPV vaccine despite poor social determinants of health or higher prevalence of risk factors such as smoking, alcohol consumption, and reduced uptake of cancer screening," the editorialists wrote. "To successfully eliminate cervical cancers, policy makers must develop, implement, or redesign programs to ensure equal access to the HPV vaccine for all individuals, regardless of their income."

England's vaccination program began in 2008 and initially used the bivalent HPV 16/18 vaccine (Cervarix), before switching to the quadrivalent HPV 6/11/16/18 vaccine (Gardasil) in 2012.

A study of the program was previously published in 2019 and showed that it was highly effective in preventing cervical cancer and CIN3. The current study looked at an additional 12 months of follow-up data -- from July 2019 through June 2020 -- but the researchers also evaluated the effectiveness of the vaccine across different levels of socioeconomic deprivation.

"In England, the social-class gradient for cervical cancer is one of the steepest of any cancers," Sasieni and colleagues wrote, noting that women in the most deprived area have had double the risk of those in the least deprived area.

Due to this higher incidence in more deprived groups, the researchers found that the most cases were prevented in the most deprived areas -- 192 and 199 for the first and second fifths -- compared with the least deprived group, for whom the vaccine prevented an estimated 61 cancers.

The number of prevented cases of CIN3 was high across all deprivation groups, but was highest for women living in more deprived areas. However, there were some differences depending on when women received the HPV vaccine. In women offered the vaccine at ages 16 to 18, the proportion of CIN3 cases prevented was 29.6% in those from the most deprived areas compared with 40.6% from the least deprived areas. There were also differences for women who received the vaccine at ages 14 to 16 and at ages 12 to 13, and between most and least deprived areas, but these differences were not as apparent.

The percentage of cancers prevented also depended on what age the women were offered the vaccine. Those offered the vaccine at ages 16 to 18 had about 26% to 29% of cancers prevented. If offered the vaccine at ages 14 to 16, about 67% to 68% of cancers were prevented, and if offered the vaccine at ages 12 to 13, about 84% to 85% of cancers were prevented.

For this study, Sasieni and colleagues analyzed the records of all women ages 20-64 living in England who were diagnosed with invasive cervical cancer or CIN3 from January 2006 through June 2020. Overall, there were 231.1 million women-years of observation over that time period, and the researchers identified 29,968 women with a diagnosis of invasive cervical cancer and 335,228 women with a diagnosis of CIN3.

Data on the women with cancer or CIN3 were aggregated by date of birth into seven birth cohorts ranging from August 1984 to June 2000. Three of the birth cohorts were eligible to receive the vaccine and were vaccinated at ages 12 to 13, 14 to 16, and 16 to 18. The older cohorts were not offered the vaccine, but were invited for screening. Vaccine coverage ranged from about 39% to 48% in the cohort that was 16 to 18 years old at vaccination, 71% to 76% in the cohort ages 14 to 16, and 81% to 88% in the cohort ages 12 to 13.

The researchers estimated that by mid-2020, HPV vaccination had prevented 687 cervical cancers and 23,192 cases of CIN3.

The main limitation of the study was that it was observational, and individual-level data on vaccination status were not available.

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