Comparison of conventional and liquid-based Pap smear methods in the diagnosis of precancerous cervical lesions

Abstract

Cervical cancer is one of the five most common cancers among women. The present study aimed to compare conventional and liquid-based Pap smear methods in 2018 in Kerman, Iran. This was a cross-sectional study. Pap smear samples (conventional Pap smear (CN) and liquid-based cytology (LBC)) were collected from five health centres in Kerman. Samples were classified into two groups of liquid and CNs, and each group was classified into normal, abnormal (including, atypical squamous cells of undetermined significance (ASCUS+), atypical squamous cells, cannot exclude high-grade squamous intraepithelial lesion (ASC-H+), low-grade squamous intraepithelial lesion (LSIL+), high-grade squamous intraepithelial lesion (HSIL+) and cancer+) and unsatisfactory. Descriptive data analysis and chi-square/Fisher's exact test were performed in SPSS 20 (SPSS Inc., Chicago, IL). Totally, 31,513 women were screened by two CN and LBC. The mean age of subjects was 39.73 ± 9.58 years. The unsatisfactory smears (1.4% versus 0.02%; p=.001) and ASCUS+ (45.1% versus 39.4%; p=.007) were more reported by conventional tests, while LSIL+ (33.1% versus 38.9%; p=.005) was reported by the LBC test. Among women who were younger than 40 years, the CIN2+ that was found by LBC was significantly more than the CN method (37.4% versus 31.7, p=.04) and among older women (older than 40 years) the CIN1+ was significantly more as well (18% versus 13.6%, p=.05). The present study showed that, although LBC had many advantages, CN is still useful. Further studies are to be suggested as a clinical trial in another population with a large number of participants to compare the diagnosing methods of cervical cancers. Impact Statement What is already known on this subject? The conventional Pap smear (CN) and liquid-based cytology (LBC) methods are the most common methods for screening cervical cancers. Previously, in some studies, LBC was reported as a better method and in some studies, traditional method was preferred. Conflicting results were found in previous articles. What do the results of this study add? LBC compared to CN could find truer abnormal cases. The superiority of the LBC method is seen in cases such as reducing unsatisfactory cases, etc. LBC compared to CN could find more CIN+. Also, LBC could find more CIN1+ among women older than 40 years and more CIN+ ≥2 among younger women. What are the implications of these findings for clinical practice and/or further research? Although LBC has many advantages and it is easier, CN is still useful and both methods are suitable for cervical abnormality and cancer detection. CN cannot be declared an outdated method.