Recent findings from the Human Papillomavirus (HPV) Vaccine Impact Monitoring Project (HPV-IMPACT), which were published by Gargano et al in the Morbidity and Mortality Weekly Report, revealed decreased incidences of cervical intraepithelial neoplasia (CIN)2+ and CIN3+ lesions among young women.

“Since 2006, when the HPV vaccine was first recommended in the United States to prevent cancers and other diseases caused by HPV, vaccination coverage has increased, and many young women vaccinated as children or adolescents have become age-eligible for cervical cancer screening,” the investigators commented. “Observed declines in cervical precancers are consistent with HPV vaccination impact and support Advisory Committee on Immunization Practices recommendations to vaccinate children against HPV at age 11 or 12 with catch-up through age 26.”  

Methods

In 2008, HPV-IMPACT began conducting population-based precancerous lesion (defined as CIN grades 2–3 and adenocarcinoma in situ, collectively CIN2+) surveillance in five sites. Participating sites perform active surveillance of the histopathology laboratories within the catchment area to identify histologically confirmed CIN2+ diagnoses. This analysis describes trends in incidence of CIN2+ and CIN3+ lesions between 2008 and 2022.

The number of women between the ages of 20 and 64 in the catchment areas was sourced from U.S. Census Bureau data, broken down by 5-year age groups. The proportions of women who were screened (ie, those who underwent a Papanicolaou [Pap] or HPV test in the preceding year), by 5-year age group, were estimated using standardized data sources and methods for all sites. To account for variations in screening by insurance coverage, estimates were weighted averages of the proportions screened among privately insured, publicly insured, and uninsured women. The investigators estimated the annual age-specific numbers of women screened by multiplying age-specific proportions screened by age-specific populations of women.

Key Findings

Between 2008 and 2022, a total of 39,977 cases of CIN2+ were reported; 13,027 (32.6%) of these cases were CIN3+. There was an annual reduction of 11.0% in CIN2+ cases per 100,000 screened women for those between the ages of 20 and 24, which, according to the investigators, represents the age group most likely to have received the vaccination; the incidence was 79.5% lower in 2022 vs 2008. The incidence of CIN2+ among women between the ages of 25 and 29 increased by 3.1% annually from 2008 to 2016 but decreased by 4.3% annually from 2016 to 2022; according to the investigators, the average annual percent change was stable.

For women between the ages of 30 and 34 as well as 35 and 39, the incidence of CIN2+ appeared to trend upward from 2008 to 2016 and then downward from 2016 to 2022; the investigators reported positive but small average annual percent changes for the entire period. They documented a significant increase in the incidence of CIN2+ from 2008 to 2022 in women between the ages of 40 and 49 as well as 50 and 64.

In general, the trends for CIN3+ vs CIN2+ appeared to be similar; among women between the ages of 20 and 24, the incidence in 2022 was 80.3% lower than that in 2008. Compared with CIN2+, the CIN3+ incidence showed a downward trend among women between the ages of 25 and 29 (average annual percent change = −3.5%); it was 37.2% lower in 2022 vs 2008.

The investigators concluded: “These data are consistent with continuing impact of the U.S. HPV vaccination program on reducing cervical precancers (including CIN3+, the outcome most proximal to cervical cancer), and are consistent with both declines in vaccine-type HPV prevalence and early observations of reductions in cervical cancer among young women. The data also suggest that precancer incidence in [groups aged at least 25] years, which were previously observed to increase through 2015, have begun to decrease. HPV vaccination and guidelines-based cervical cancer screening are important tools for cervical cancer prevention.”

Julia W. Gargano, PhD, of National Center for Immunization and Respiratory Diseases, U.S. Centers for Disease Control and Prevention, is the corresponding author of the Morbidity and Mortality Weekly Report article.

Disclosure: For full disclosures of the authors, visit cdc.gov.