Outcomes in cervical screening using various cytology technologies: what's age got to do with it?

Unlike for human papillomavirus screening, little is known about the possible age-dependent variation in the outcomes of cervical cytology screening. The aim of our study was to describe age-related outcomes of five cytological technologies in a population-based screening program targeting women aged 23-59 years. All cervical cytology from women residing in Copenhagen has been analyzed in the laboratory of the Department of Pathology, Hvidovre University Hospital. We studied five technology phases: (1) conventional cytology with manual reading, (2) conventional cytology with 50% automatically signed out as normal, (3) liquid-based cytology (LBC) with 50% automatically signed out as normal, (4) LBC with 25% automatically signed out as normal, and (5) LBC with 25% automatically signed out as normal and with 16 preselected areas for attention in manual reading. We calculated proportion of samples with atypical squamous cells of undetermined significance or worse (≥ASCUS) by age and technology phase. We included 391 140 samples. The proportion of ≥ASCUS increased steadily from 3.8% in phase 1 to 6.0% in phase 5. This pattern varied considerably across age groups. In women aged 23-34 years, the proportion almost doubled, relative proportion 1.96 (95% confidence interval: 1.84-2.08). An opposite development was seen in women aged 45-59 years, relative proportion 0.68 (95% confidence interval: 0.57-0.82). Technological upgrading of cytology strongly affected the outcome of cervical screening for young women. If corroborated with data from other laboratories, these findings call for caution in implementation of new cytology screening technologies.