Improved understanding of the natural history of cervical carcinogenesis, and knowledge of the relative performance of different screening tests implies superiority of the high risk human papillomavirus (hrHPV) test over cytology in cervical cancer screening. Five-year hrHPV testing in primary screening was implemented instead of the standard of care, triennial Pap-smear screening, from February 1st, 2015 in Norway. Updated results from on-going surveillance will be presented in the conference.
In 2014, the same HPV test, biobank solutions, similar communication strategies etc., were adapted by screening units implementing new cervical cancer screening technology for approximately 1/4 of eligible Norwegian female population (in four counties). Information about the target population, such as date of birth and address is available for administration of the program. Based on date of birth (odd and even days), which equals to randomized allocation, 50% of 34-69 years old women receive cytology and 50% hrHPV test in screening. Every cytology, hrHPV, and histology result is reported to the Cancer Registry of Norway for coordination and surveillance.
By the end of 2015 more than 60,000 women, 34 to 69 years of age, were screened with either hrHPV or cytology in counties implementing hrHPV screening; attendance rates were comparable; the overall hrHPV positivity rate in HPV arm was 6,7%; reflex cytology in triage of hrHPV positives indicated high proportion of abnormalities, leading to about 4% colposcopy referral in HPV screening, twice as in cytology screening; there was significantly more CIN2+ diagnosed in the HPV arm. Altogether, 30 cancers were diagnosed, of which 16 were in the cytology and 14 in the HPV arm.
Careful preparation has translated to smooth transition from cytology to HPV testing. Quality assessment of the cytology smear diagnostics in hrHPV positives might be useful to evaluate the extent of the emerging diagnostic shift, likely to be result because of readily known hrHPV status. Gradual and randomized implementation alleviates workload increase for the coloposcopy and pathology services and allows direct comparison of effect indicators between two screening modalities.