Cytohistological findings in HPV-negative cases from HPV primary screening programme: quality assurance study

To evaluate the risk of false HPV-negative results and possible related morphological abnormalities in HPV primary cervical cancer screening. Out of 53,661 HPV-negative cases, 5469 (10.2%) randomly selected cytology slides were evaluated as a part of the quality assurance protocol. The Bethesda category negative for intraepithelial lesion or malignancy (NILM) in the HPV-negative cases given was present in 95.4%. Due to cytology other than NILM, 0.4% of cases were referred to colposcopy and 4.2% to the follow-up in one year. In the follow-up HPV negativity and NILM cytology was present in 88.3% of attended women. Cases other than HPV negative and NILM were referred to colposcopy. One biopsy-proven histological HSIL was found in the first round and one in follow-up screening. More comprehensive genotyping of HSIL cases revealed genotypes 69 and 11. Only two HPV test negative cases with histological HSIL were revealed forming 0.04% of quality control group. In both cases, HPV genotype not included in screening tests was found. According to the results, the primary HPV test with cytology triage is an efficient and specific method for cervical cancer screening despite of the fact that some non-high-risk genotypes are missed.