A new study has found that after adjusting for changes in screening, there was a decrease in incidence of all grades of cervical intraepithelial neoplasia (CIN) for women 15- to 19-years old, and CIN grade 2 in women 20- to 24-years old.
Untreated human papillomavirus (HPV) infection has been identified as a leading cause of developing cervical intraepithelial neoplasia (CIN), which can lead to invasive cervical cancer. While several studies have documented the success of HPV vaccination in preventing the viral infection and development of low-grade and high-grade CIN, the impact of subsequent reduced screening rates have not been examined. Now, a new study in JAMA Oncology has found that after adjusting for changes in screening, there was a decrease in incidence of all CIN grades for women 15- to 19-years old, and CIN grade 2 in women 20- to 24-years old.
For their study, the authors captured data from the New Mexico HPV Pap Registry—the only surveillance system in the Unites States so far that captures data on HPV screening and CIN rates since the HPV vaccine was first introduced in 2007. The average uptake of all 3 doses of HPV vaccine among females aged 13 to 17 in New Mexico was 40%. Of the 658,093 women in New Mexico who underwent cervical cytologic testing between 2007 and 2014, 33.4% were younger than 30 years when they were screened. The biopsy results were classified as:
Of the entire population that was screened, the authors observed the following in 15- to 29-year-old women during the entire study period:
Following adjustments for screening rates, the CIN incidence in the 15- to 19-year age group saw a significant reduction in CIN during the study period:
The authors also observed a drop from 1027.7 to 627.1 (APC, −6.3; 95% CI, −10.9 to −1.4; P = .02) in the incidence of CIN2 among women 20- to 24-years old.
Based on their findings, the authors conclude that reductions were greater than what they had anticipated, supporting vaccine cross-protection, with efficacy of less than 3 vaccine doses and herd immunity contributions. “The study suggests a rapidly approaching need to revisit guidelines for cervical cancer screening in the United States, including increasing the age to begin screening.” This stems from the fact that current guidelines do not differentiate between vaccinated and unvaccinated women.
Bernard V, Castle PE, Jenison SA, et al. Population-based incidence rates of cervical intraepithelial neoplasia in the human papillomavirus vaccine era [published online September 29, 2016]. JAMA Oncology. doi:10.1001/jamaoncol.2016.3609.