Risk of progression of cervical intraepithelial neoplasia grade 2 in human papillomavirus-vaccinated and unvaccinated women: a population-based cohort study.

BACKGROUND: Many countries have implemented active surveillance (ie, leaving the lesion untreated) as an option among younger women with cervical intraepithelial neoplasia grade 2 because regression rates are high and excisional treatment increases the risk for preterm birth in subsequent pregnancies. However, early identification of women at increased risk for progression to cervical intraepithelial neoplasia grade 3 or worse is important to ensure timely treatment. Because women who have received a human papillomavirus vaccine have a lower risk for cervical cancer, they may have a lower risk for progression of untreated cervical intraepithelial neoplasia grade 2 to cervical intraepithelial neoplasia grade 3 or worse. OBJECTIVE: This study aimed to investigate if women who received a human papillomavirus vaccine and who are undergoing active surveillance for cervical intraepithelial neoplasia grade 2 are less likely to progress to cervical intraepithelial neoplasia grade 3 or worse when compared with women who did not receive the vaccine. STUDY DESIGN: We conducted a population-based cohort study in Denmark using data from national health registers. We identified all women aged 18 to 40 years who were undergoing active surveillance for cervical intraepithelial neoplasia grade 2 from January 1, 2007, to December 31, 2020. Women with a previous record of cervical intraepithelial neoplasia grade 2 or worse, hysterectomy, or a loop electrosurgical excision procedure were excluded. Exposure was defined as having received ≥1 dose of a human papillomavirus vaccine at least 1 year before the cervical intraepithelial neoplasia grade 2 diagnosis. We used cumulative incidence functions to estimate the risk for progression to cervical intraepithelial neoplasia grade 3 or worse within 28 months using hysterectomy, emigration, and death as competing events. We used modified Poisson regression to calculate crude and adjusted relative risks of progression during the 28-month surveillance period. Results were stratified by age at vaccination and adjusted for index cytology, disposable income, and educational level. RESULTS: The study population consisted of 7904 women of whom 3867 (48.9%) were vaccinated at least 1 year before a diagnosis of cervical intraepithelial neoplasia grade 2. At the time of cervical intraepithelial neoplasia grade 2 diagnosis, women who were vaccinated were younger (median age, 25 years; interquartile range, 23-27 years) than those who were not (median age, 29 years; interquartile range, 25-33 years). The 28-month cumulative risk for cervical intraepithelial neoplasia grade 3 or worse was significantly lower among women who were vaccinated before the age of 15 years (22.9%; 95% confidence interval, 19.8-26.1) and between the ages of 15 and 20 years (31.5%; 95% confidence interval, 28.8-34.3) when compared with women who were not vaccinated (37.6%; 95% confidence interval, 36.1-39.1). Thus, when compared with women who were not vaccinated, those who were vaccinated before the age of 15 years had a 35% lower risk for progression to cervical intraepithelial neoplasia grade 3 or worse (adjusted relative risk, 0.65; 95% confidence interval, 0.57-0.75), whereas women who were vaccinated between the ages of 15 and 20 years had a 14% lower risk (adjusted relative risk, 0.86; 95% confidence interval, 0.79-0.95). For women who were vaccinated after the age of 20 years, the risk was comparable with that among women who were not vaccinated (adjusted relative risk, 1.02; 95% confidence interval, 0.96-1.09). CONCLUSION: Women who were vaccinated and who were undergoing active surveillance for cervical intraepithelial neoplasia grade 2 had a lower risk for progression to cervical intraepithelial neoplasia grade 3 or worse during 28 months of follow-up when compared with women who were not vaccinated but only if the vaccine was administered by the age of 20 years. These findings may suggest that the human papillomavirus vaccination status can be used for risk stratification in clinical management of cervical intraepithelial neoplasia grade 2.

Clinical course of cervical intraepithelial neoplasia grade 2: a population-based cohort study.

BACKGROUND: Cervical intraepithelial neoplasia grade 2 has historically been the threshold for surgical excision, but because of high regression rates, many countries are transitioning to active surveillance. However, estimates for regression rates are based on small studies with heterogeneous definitions of regression and progression. OBJECTIVE: This study aimed to describe regression and progression rates of cervical intraepithelial neoplasia grade 2 using nationwide healthcare registry data. STUDY DESIGN: This was a nationwide population-based cohort study on women aged 18 to 40 years who had undergone active surveillance for cervical intraepithelial neoplasia grade 2 in Denmark from 1998 to 2020. This study excluded women with a previous record of cervical intraepithelial neoplasia grade 2 or worse or surgical excision. Cumulative incidence functions were used to estimate the rates of regression and progression at 6, 12, 18, and 24 months after diagnosis. In addition, a modified Poisson regression was used to estimate the crude and adjusted relative risks of progression within 24 months stratified by index cytology and age. RESULTS: During the study period, 11,056 women underwent active surveillance, 6767 of whom regressed and 3580 of whom progressed within 24 months. This corresponded to regression rates of 62.9% (95% confidence interval, 61.9-63.8) and progression rates of 33.3% (95% confidence interval, 32.4-34.2) at 24 months of follow-up. Most women regressed (90%) or progressed (90%) within the first 12 months. Women with high-grade index cytology had a higher risk of progression than women with normal index cytology (adjusted relative, 1.58; 95% confidence interval, 1.43-1.76), whereas there was no difference in the risk of progression between women aged 30 and 40 years and women aged 23 to 29 years (adjusted relative risk, 0.98; 95% confidence interval, 0.88-1.10). CONCLUSION: The observed high regression rates of cervical intraepithelial neoplasia grade 2 supported the transition in clinical management from surgical excision to active surveillance, particularly among women with low-grade or normal index cytology.

Known Benefits and Unknown Risks of Active Surveillance of Cervical Intraepithelial Neoplasia Grade 2.

Cervical intraepithelial neoplasia grade 2 (CIN 2) is an equivocal diagnosis with high interobserver variation. Owing to high regression rates of 50%, many countries recommend active surveillance of CIN 2, especially in women younger than age 25-30 years, where regression rates are even higher (ie, 60%). Additionally, excisional treatment is associated with increased risk of reproductive harm, particularly preterm birth. Active surveillance typically consists of semi-annual follow-up visits for up to 2 years, including colposcopy and either cytology, testing for human papillomavirus, or both. Excisional treatment is recommended for progression or persistent disease after 2 years. Because active surveillance in younger women is relatively new, knowledge on subsequent risk of cervical cancer is limited. Considering human papillomavirus latency, women undergoing active surveillance might be at higher risk of cervical cancer than women undergoing excisional treatment. Furthermore, there are limited data describing preferences of women for the management of CIN 2, and it is also unclear how active surveillance may affect planning for future pregnancy. In this context, biomarkers for risk stratification of CIN 2 into either high or low probability of progression would allow for targeted treatment. Currently, immunohistochemical staining for p16 is used to clarify the histologic diagnosis, but whether it or other biomarkers can be used for risk-stratification in clinical management of women with CIN 2 remains unknown. In conclusion, active surveillance of CIN 2 needs further investigation, including understanding the long-term cervical cancer risk and evaluation of markers that may enable risk stratification of CIN 2.