At the beginning of 2017 The Netherlands converted to hrHPV-based cervical cancer screening with cytological triage of positive cases. A strong increase in colposcopy referrals is foreseen most of which seem unwarranted. Thus, reduction of unjustified referrals will have priority. Koilocytosis is considered as a cytopathic effect of a productive HPV infection but the relation with subsequent diagnosis of high-grade Cervical Intraepithelial Neoplasia (CIN) is unclear. The aim of this study was to investigate if the risk for CIN3 or more (CIN3+) differs between hrHPV-positive ASC-US/LSIL with or without koilocytosis and whether the presence of koilocytosis could justify a more conservatively follow-up regime.
Retrospective cohort study, using data from the nationwide network and registry of histo- and cytopathology in The Netherlands (PALGA). HrHPV-positive ASC-US/LSIL follow-up cytology of 1 201 women was used from the former cytology-based cervical screening programme. Reporting of koilocytosis was assessed as well as detection rates of CIN1 or less, CIN2 and CIN3+, stratified by the presence or absence of koilocytosis. Crude and adjusted odds ratios (ORs) were calculated.
Koilocytosis was present in 40.1% of hrHPV-positive ASC-US and 45.9% of hrHPV-positive LSIL. CIN3+ is significantly less often found when koilocytosis was reported (7.8% for hrHPV-positive ASC-US with koilocytosis versus 15.8% without koilocytosis). For hrHPV-positive LSIL this was 11.7% versus 20.2%. The crude and adjusted ORs for CIN3+ were 0.45 for hrHPV-positive ASC-US and 0.52 for hrHPV-positive LSIL.
The presence of koilocytosis is a negative predictor of CIN3+. The risk of hrHPV-positive ASC-US combined with koilocytosis for CIN3+ is in the same range as hrHPV-positive/cytology negative cases and these cases could be followed conservatively by repeat cytology after 6 months. However, the results of this study should be confirmed by the first data derived from the new HPV-based screening programme.