Changes in Cervical Cytology Results and Human Papillomavirus Types Among Persons Screened for Cervical Cancer, 2007 and 2015-2017

Abstract

Objectives: Since 2006, the US human papillomavirus (HPV) vaccination program has led to decreases in HPV infections caused by high-risk vaccine-targeted HPV types (HPV 16/18). We assessed differences in high-risk HPV prevalence by cervical cytology result among 20- to 24-year-old persons participating in routine cervical cancer screening in 2015-2017 compared with 2007.

Materials and methods: Residual routine cervical cancer screening specimens were collected from 20- to 24-year-old members of 2 integrated healthcare delivery systems as part of a cross-sectional study and were tested for 37 HPV types. Cytology results and vaccination status (≥1 dose) were extracted from medical records. Cytology categories were normal, atypical squamous cells of undefined significance, low-grade squamous intraepithelial lesions (SIL), or high-grade SIL/atypical squamous cells cannot exclude high-grade SIL. Prevalences of HPV categories (HPV 16/18, HPV 31/33/45/52/58, HPV 35/39/51/56/59/66/68) were estimated by cytology result for 2007 and 2015-2017.

Results: Specimens from 2007 (n = 4046) were from unvaccinated participants; 4574 of 8442 specimens (54.2%) from 2015-2017 were from vaccinated participants. Overall, HPV 16/18 positivity was lower in 2015-2017 compared with 2007 in all groups: high-grade SIL/atypical squamous cells cannot exclude high-grade SIL, 16.0% vs 69.2%; low-grade SIL, 5.4% vs 40.1%; atypical squamous cells of undefined significance, 5.0% vs 25.6%; and normal, 1.3% vs 8.1%. Human papillomavirus 31/33/45/52/58 prevalence was stable for all cytology groups; HPV 35/39/51/56/59/66/68 prevalence increased among low-grade SIL specimens (53.9% to 65.2%) but remained stable in other groups.

Conclusions: Prevalence of vaccine-targeted high-risk HPV types 16/18 was dramatically lower in 2015-2017 than 2007 across all cytology result groups while prevalence of other high-risk HPV types was mainly stable, supporting vaccine impact with no evidence of type replacement.

Figure 1:

Prevalence of high-risk HPV categories by cytology result among 20–24-year-old participants, 2007 and 2015–2017, a) HPV 16/18, b) 5 additional 9vHPV types, c) other high-risk HPV, d) any high-risk HPV. ASCUS, atypical squamous cells of undefined significance; LSIL, low-grade squamous intraepithelial lesions; HSIL, high-grade squamous intraepithelial lesions; ASC-H, atypical squamous cells, cannot exclude high-grade squamous intraepithelial lesion. HPV 16/18, 5 additional 9vHPV types (HPV 31/33/45/52/58), other high-risk HPV (HPV 35/39/51/56/59/66/68), and any high-risk HPV (HPV 16/18/31/33/35/39/45/51/52/56/58/59/66/68). *Significant difference in prevalence between 2007 and 2015–2017 using Fisher’s Exact test (p-value <0.05) Numbers in parentheses represent number of specimen positive for the relevant HPV category/total number of specimens in the relevant cytologic outcome-time period group. **Among HSIL specimens that were negative for high-risk HPV, specimens were positive for the following types: three were positive for HPV 53 and HPV 73, one for HPV 67, one for HPV 82 and HPV 89, one for HPV 64 and HPV 89, one for HPV 61 and HPV 82, and one for HPV82. Three were negative for all 37 HPV types.