National experience in the first two years of primary human papillomavirus (HPV) cervical screening in an HPV vaccinated population in Australia: observational study

Abstract

Objective

To review the first two years of the primary human papillomavirus (HPV) cervical screening programme in an HPV vaccinated population.

Design

Observational study.

Setting

Australia.

Participants

3 745 318 women with a primary HPV test between 1 December 2017 and 31 December 2019; most women aged <40 years had previously been offered vaccination against HPV16 and HPV18.

Interventions

Primary HPV screening with referral if HPV16 or HPV18 (HPV16/18) positive and triage with liquid based cytology testing (threshold atypical squamous cells-cannot exclude high grade squamous intraepithelial lesion) for women who were positive for high risk HPV types other than 16/18. A 12 month follow-up HPV test was recommended in triaged women with a negative or low grade cytology result, with referral if they tested positive for any high risk HPV type at follow-up.

Main outcome measures

Proportion of women who had attended for their first HPV screening test, tested positive, and were referred for colposcopy; and short term risk of detecting cervical intraepithelial neoplasia (CIN) grade 2 or worse, CIN grade 3 or worse, or cancer.

Results

54.6% (n=3 507 281) of an estimated 6 428 677 eligible women aged 25-69 had undergone their first HPV test by the end of 2019. Among those attending for routine screening, positivity for HPV16/18 and for HPV types not 16/18 was, respectively, 2.0% and 6.6% in women aged 25-69 (n=3 045 844) and 2.2% and 13.3% in highly vaccinated cohorts of women aged 25-34 (n=768 362). Colposcopy referral (ages 25-69 years) was 3.5%, increasing to an estimated 6.2% after accounting for women who had not yet had a 12 month repeat test. Cervical cancer was detected in 0.98% (456/46 330) of women positive for HPV16/18 at baseline, including 0.32% (89/28 003) of women with HPV16/18 and negative cytology. Women with HPV types not 16/18 and negative or low grade cytology at both baseline and 12 months were at low risk of serious disease (3.4% CIN grade 3 or worse; 0.02% cancer; n=20 019) but estimated to account for 62.0% of referrals for this screening algorithm.

Conclusions

Colposcopy referral thresholds need to consider underlying cancer risk; on this basis, women with HPV16/18 in the first round of HPV screening were found to be at higher risk regardless of cytology result, even in a previously well screened population. Women with HPV types not 16/18 and negative or low grade cytology showed a low risk of serious abnormalities but constitute most referrals and could be managed safely with two rounds of repeat HPV testing rather than one. HPV16/18 driven referrals were low in HPV vaccinated cohorts.