Reasons for truly negative cytology reports preceding the diagnoses of invasive cervical cancer-Results of a false-negative cytology audit in Polish Cervical Cancer Screening Programme.

BACKGROUND

False-negative (FN) results in cervical cancer (CC) screening pose significant risk for participants and should be audited. The aim of the study was to analyse the results of audit of FN slides collected in 2010-2013 in Polish Cervical Cancer Screening Program (CCSP) and to seek for risk factors of obtaining true-negative result (TN; not containing abnormal cells as confirmed in audit) before CC diagnosis.

METHODS

Screening database was merged with National Cancer Registry to identify negative slides preceding histologically confirmed CC diagnosis up to 42 months. Two blinding slides were randomly assigned per each FN. The whole set was reassessed independently by three pathologists with 30 years of experience in cytology evaluation. Final audit result was established in the case of ≥2 coherent reports. Agreement rates and kappa (κ) coefficients were calculated. Logistic analysis of risk factors for obtaining TN result was performed.

RESULTS

Of 374 included FNs, 204 were considered abnormal (54.6%) and 91 were confirmed negative for intraepithelial neoplasia (24.3%). Agreement between experts was moderate for FNs (κ = 0.266) and fair for blinding slides (κ = 0.142) when grouping abnormal slides. Adenocarcinoma diagnosis elevated the risk of TN result (OR = 3.83); detection of macroscopic changes on the cervix and smoking lowered the risk (OR = 0.39, OR = 0.40 respectively).

CONCLUSIONS

Misinterpretation was the main reason for FN cytology in the CCSP which indicated the need of further personnel training to increase screening quality. Rather low agreement between auditors requires further insight. A standardised process of auditors' selection should be planned to increase audit quality.