Self-sampling for Human Papillomavirus (HPV) offered to women who do not participate in organized cervical cancer screening is an increasingly popular method to increase screening coverage. The rationale behind it is that under-screened women harbour a high proportion of undetected precancerous lesions since ~50% of disease is routinely detected in underscreened women. In 2014 the “Copenhagen Self-sampling initiative” (CSi) offered HPV self-sampling to screening non-attenders in the Capital Region of Denmark. We compared the ≥CIN2-detection rate between screening non-attenders, who participated in self-sampling, and women attending routine screening (The HORIZON cohort).
23,632 women who were qualified as screening non-attenders in the Capital Region were offered HPV-based self-sampling using an Evalyn brush (Rovers, Oss the Netherlands). 4824 (20.6%) women returned a self-sample brush, and HR-HPV-positive women were referred for cytology and HPV-testing as follow-up. The entire cohort and a reference cohort (3347 routinely screened women from the HORIZON cohort), were followed for histopathology-confirmed ≥CIN2. Odds ratio and positive predictive value of ≥CIN2-detections between the two populations were estimated
Women participating in self-sampling had the same ≥CIN2-detection rate as routinely screened women (OR= 1.03; 95% CI: 0.75-1.40). The positive predictive value of ≥CIN2 detections was, however, higher in screening non-attenders than routinely screened women (36.5% vs. 25.6%, respectively). Among all detected ≥CIN2, women were slightly more likely to have ≥CIN3 detected if they were CSi-attenders (78.6% of all ≥CIN2 diagnoses were ≥CIN3), than if they were routinely screened (HORIZON population) (72.1%).However, in total, 18 women were diagnosed with cervical cancer in the screening non-attenders population, versus only one in the reference population.
Self-sampling to non-attenders had similar detection rates for ≥CIN2 as routine cytology-based screening, reinforcing the importance of self-sampling to screening non-attenders in organized cervical cancer screening. The proportion of high-grade CIN lesions among all biopsies was high, demonstrating the efficiency of the approach. The major finding was a large increase in cancer detection in the self-sampled group, which underlines the importance of reaching underserved women to reduce morbidity and mortality from cervical cancer.