Cervical cancer rates drop significantly among vaccinated women

By Pooja Toshniwal PahariaMay 16 2024Reviewed by Lily Ramsey, LLM

In a recent study published in BMJ, researchers in England assessed the efficiency of the human papillomavirus (HPV) vaccination program in reducing the prevalence of cervical cancers and grade 3 cervical intraepithelial neoplasms (CIN3) across socioeconomic groups.

Study: Effect of the HPV vaccination programme on incidence of cervical cancer and grade 3 cervical intraepithelial neoplasia by socioeconomic deprivation in England: population based observational study. Image Credit: Prostock-studio/Shutterstock.com

Background

The HPV vaccination, introduced in 2008 in England, has considerably reduced the prevalence of cervical cancer and grade 3 cervical intraepithelial neoplasia (CIN3), notably among females. The decrease was the highest in groups with the highest vaccination uptake and the youngest age at immunization.

The social-class gradient for cervical cancer incidence in England is one of the steepest, and there are worries that HPV vaccination may assist those who are most at risk the least.

The National Health Service (NHS) of England aims to eliminate health inequalities, and low HPV vaccination uptake among vulnerable individuals may exacerbate health disparities.

Cervical screening uptake is low among younger females in the poorest regions, resulting in lower detection rates of screen-identified cervical cancers and CIN3 at age 25 than in less socioeconomically deprived areas.

HPV vaccine coverage has been consistently high, but it is critical to explore if immunization, including the indirect impacts of high uptake, is helping to minimize health disparities.

About the study

In the present population-level observational study, researchers examined whether HPV vaccines reduced or increased cervical disease inequities.

The researchers reproduced findings from a cancer registry analysis to investigate if the previously observed high HPV vaccine efficacy persisted after an additional follow-up year.

They used combined data to evaluate the impact of the immunization program on socioeconomic disadvantage. The study included female residents of England aged 20 to 64 who were diagnosed with cervical cancer (n=29,968) or CIN3 (n=335,228) from January 2006 to June 2020.

The primary endpoints were invasive cervical cancer incidences and CIN3 occurrences. The researchers utilized the index of multidimensional deprivation (IMD) to quantify socioeconomic deprivation across domains such as health, employment, and income.

The index rates lower superoutput regions from most to least socioeconomically deprived and divides them into five groups, with groups 1 and 5 representing the 20% poorest and 20% richest areas, respectively.

The researchers used the International Classification of Diseases, tenth revision (ICD-10) codes from the NHS England National Disease Registration Service (NDRS) database to detect cervical cancers and CIN3.

They obtained middle-year estimations of the female population from the United Kingdom Office for National Statistics (ONS) website. They used age-period-cohort Poisson regression modeling to investigate CIN3 and cervical cancer occurrences.

Results

Among females routinely offered vaccines at 12 to 13 years of age, the adjusted age-standardized incidence rates for cervical cancers and CIN3 were 84% and 94% lower over an additional follow-up year (July 1, 2019, to June 30, 2020) compared to the reference group of females not offered HPV vaccines. By the middle of 2020, HPV vaccines would have saved predicted 687 cervical malignancies and 23,192 CIN3s.

The researchers found the highest cervical cancer rates among females from the most socioeconomically deprived regions (192 and 199 for the first and second fifths, respectively) and the fewest in women in the least deprived fifth (61 cancers prevented), but the vaccination program had a significant impact across all deprivation levels.

CIN3 incidences decreased more among females receiving catch-up vaccinations in the least socioeconomically deprived regions than in the most. The number of women with CIN3 averted was high across all deprivation categories and highest among women living in the most impoverished areas: 5,121 and 5,773 in the first and second-fifths, respectively, compared to 4,173 and 3,309 in the fourth and fifth fifths.

The significant decline in cervical cancer incidence from highly deprived regions to less deprived regions observed in the reference group of unvaccinated individuals was not apparent among those who received the vaccination.

Conclusion

Based on the study findings, the HPV vaccination program in England has considerably lowered cervical malignancy and neoplasia rates across all socioeconomic levels, particularly among females who had regular vaccines.

However, the highest rates persisted among women in the most impoverished neighborhoods. Researchers discovered that the significant downward gradient from high to low impoverishment observed in the reference unvaccinated sample did not exist among those offered immunization.

The efficacy of national HPV immunization persisted in the extra year of follow-up (between July 2019 and June 2020), verifying earlier findings and encouraging using more restricted cervical screening in cohorts with high vaccine coverage aged 12–13 years.