Validation of a new HPV self-sampling device for cervical cancer screening: The Cervical and Self-Sample In Screening (CASSIS) study

Abstract

Objective: We compared the self-sampling performance of the newly designed HerSwab™ device with a physician-collected cervical sample and another self-sample using the cobas® PCR Female swab for the detection of cervical intraepithelial neoplasia (CIN) and cancer.

Methods: Women referred for colposcopy at McGill University affiliated hospital clinics collected two consecutive self-samples, one with HerSwab™ and one with cobas® swab, after receiving instructions. The order of sampling was randomized. The colposcopist then collected a cervical sample and conducted a colposcopic examination. Samples were tested for human papillomavirus (HPV) DNA. Sensitivity and specificity to detect CIN2+ and respective 95% confidence intervals (CI) were calculated to compare sampling approaches. The HPV testing agreement between samples was measured using the Kappa statistic.

Results: Of 1217 women enrolled, 1076 had complete results for HPV and cytology; 148 (13.8%) had CIN1, 147 (13.7%) had CIN2/3, and 5 (0.5%) had cancer. There was very good agreement between methods for HPV detection (HerSwab™ versus physician: kappa=0.84; cobas® swabs versus physician: kappa=0.81; HerSwab™ versus cobas® swabs: kappa=0.87). The sensitivity of HPV detection for CIN2+ was 87.6% (95%CI: 79.8-93.2) with self-sampling using HerSwab™, 88.6% (95%CI: 80.9-94.0) with self-sampling using the cobas® swab, and 92.4% (95%CI: 85.5-96.7) with physician sampling. Corresponding estimates of specificity were 58.1% (95%CI: 54.1-62.1), 55.0% (95%CI: 50.9-59.0) and 58.7% (95%CI: 54.6-62.6). Cytology (ASC-US or more severe) done on the physician-collected specimen was 80.2% (95%CI: 70.8-87.6) sensitive and 61.4% (95%CI: 57.2-65.5) specific for CIN2+.

Conclusions: The HerSwab™ had good agreement with physician sampling in detecting HPV, and adequate performance in detecting high-grade lesions among women referred to colposcopy for abnormal cytology.

Keywords: Cervical cancer; Cervical intraepithelial neoplasia; Cervical screening; HPV DNA testing; Self-sampling.