Re-Evaluating the Predictive Values of Pap-smear for Diagnosis and LLETZ Margin Status for Management of Precancerous Cervical Lesions

Abstract

Background: The incidence of HPV infection, precancerous cervical lesions and cervical cancer is relatively high in sub-Saharan African countries. There is significant variability among such countries and worldwide in the accuracy of screening for precancerous cervical lesions and test for cure after excision. Implementation and interval between these procedures also vary. Objective: The aim of this study was to determine the predictive values of Pap-smear for screening and LLETZ for proof-of-cure in a South African hospital setting. Patients and Methods: In the current study, the positive and negative predictive values of Pap-smear screening for the identification of low-grade and high-grade squamous epithelial cervical lesions (LSIL and HSIL, respectively) and Large Loop Excision of the Transformation Zone (LLETZ) procedures for the assessment of residual lesions were determined in a South African hospital setting. Patients referred to the hospital because of abnormal Pap-smear results were included. Results: Pap-smear screening was found to have a positive predictive value of over 90% for HSIL, indicating that this procedure is a reasonable low-cost method of screening for cervical cancer in this setting. Conversely, LLETZ displayed more modest PPV and NPV of 58% and 62%, respectively, for prediction of residual and completely excised lesions. Conclusion: Pap-smear testing had reasonable PPV (>90% for HSIL) to be effectively used as a low-cost screening method in a middle- to low-income South African hospital setting. The predictive values of LLETZ margin status was questionable, justifying careful follow-up after negative margin status. These results justify the consideration of post-LLETZ follow up pap-smear within 3–4 months for both positive and negative margin status, this may prevent under or over treatment of women with precancerous cervical lesions.