Image: The Hybrid Capture 2 modular system used for processing the digene HC2 HPV DNA Test of human papillomavirus infections (Photo courtesy of Qiagen).
Human papillomavirus (HPV) testing detects a higher number of precancerous cervical lesions than cytology-based Papanicolaou (Pap) smears in a female population including a proportion offered HPV vaccination according to a new study.
Many countries are currently considering switching from classic Pap tests to primary HPV tests for cervical cancer screening, based on the strong evidence linking cervical abnormalities and infection with certain HPV types, and data suggesting that HPV tests detect more high-grade precancerous lesions.
Scientists collaborating with those at the Victorian Cytology Service, Melbourne, Australia) randomized cervical samples from 4,995 women aged 25-64 in Australia, in a 1:2:2 ratio, to be analyzed by either cytology (with HPV testing of low-grade abnormalities), HPV testing with partial genotyping of the virus for the highest risk types HPV16 and 18, and cytology (for participants with other high-risk HPV genotypes), or HPV testing with partial genotyping and dual-stained cytology. In the first screening round of the trial, the scientists assessed the rates of women being referred for further testing and of detection of high-grade cervical intraepithelial neoplasia precancerous lesions (CIN2+).
For liquid-based cytology (LBC) screening and triage testing, ThinPrep was used. For HPV screening and triage testing, both the digene Hybrid Capture 2 (HC2) and Cobas 4800 technologies were used since the objectives of the study included laboratory evaluation of different HPV test technologies. The Cobas 4800 was used for the initial 3,104 (78%) of the total 4,003 HPV-screened women, and HC2 was used for the remainder.
The investigators found that for the cytology group, the overall referral and detected CIN2+ rates were 27/995 (2.7%) and 1/995 (0.1%) respectively; for the HPV testing and cytology group these were 75/1992 (3.8%)and 20/1992 (1.0%) and for the HPV and dual-stained cytology group these were 79/2008 (3.9%) and 24/2008 (1.2%). The team found that, in the first round of screening, detection of CIN2+ was significantly increased with HPV testing as compared with cytology, while referral was non-significantly increased. Adverse events were rare, and the one case of early-stage cervical cancer in the HPV testing plus cytology group was detected as appropriate by screening.
Karen Canfell, D.Phil, a professor of cancer epidemiology and lead author of the study, said, “These findings provide initial confirmation of an improved performance of primary HPV screening compared to cytology screening in settings with HPV-vaccinated populations. These findings support the planned imminent introduction of cervical screening by HPV testing in Australia which will occur at the end of 2017.” The study was published on September 19, 2017, in the journal Public Library of Science Medicine.
Victorian Cytology Service