A randomised trial of HPV self-sampling among non-attenders in the Slovenian cervical screening programme ZORA: Comparison of the intention-to-screen response rates and histological outcomes between three different screening approaches
Introduction: To overcome obstacles within the Slovenian organised cervical cancer screening programme, a randomised pilot study of human papillomavirus (HPV) self-sampling among non-attendees in two Slovenian regions was performed, comparing three different screening approaches.
Materials and methods: Non-attenders aged 30‒64 years from two Slovenian regions were randomised to two HPV self-sampling groups – the opt-in I1 group (n = 14,400) and the opt-out I2 group (n = 9,556), with a control P group (n = 2,600). Self-taken samples were analysed using the Hybrid Capture 2 assay. HPV-positive women were invited to a colposcopy clinic. The overall and type-specific intention-to-screen response rates and histological outcomes with a positive predictive value (PPV) according to the women’s age, the screening approach, the level of protection resulting from previous screening history, and the region of residence were assessed.
Results: Of the 26,556 women enrolled, 8,972 (33.8%) responded with self-sample for HPV testing and/or traditional cytology within one year of enrolment. The intention-to-screen response rates were 37.7%, 34.0% and 18.4% (p <0.050) for I2, I1 and P groups, respectively. The CIN2+ was diagnosed in 3.9/1,000, 3.4/1,000, and 3.1/1,000 women from the I2, I1 and P group (p >0.050), respectively. The PPV of the HPV self-sampling was 12.0% and 9.6% for CIN2+ and CIN3+, respectively. The highest PPV was obtained in non-attenders in screening programme for more than 10-years and concordant results of HPV testing with 40.8% for CIN2+ and 38.8% for CIN3+.
Conclusion: The results of our study show that a high response rate to HPV self-sampling can be achieved also in an opt-in approach, if women are encouraged to choose between self-sampling at home and screening with gynaecologist. In addition, clinically important risk difference for a high-grade cervical lesion exists in the case of a positive result of HPV testing on self-taken samples, depending on the length of the interval since last screening cytology. Stratified management of these women should be strongly considered. Women who were not screened with cytology for 10 years or more should be referred to immediate colposcopy for histology verification instead to delayed re-testing.
Keywords: cervical cancer prevention, screening programme, non-attenders, cytology, HPV test at home, self-sampling