Comparative study of liquid based cytology and pap smear in cancer cervix screening

OBJECTIVE: Cervical cancer is a preventable disease. Screening for precancerous lesion of cancer cervix is one of the secondary prevention activities. In 1940’s Pap smear was introduced for cancer cervix screening. The imperfect sensitivity and variable smear quality of Conventional Pap collection lead to the development of Liquid Based Cytology (LBC). The aim of this study is to evaluate liquid based cytology and to compare the sensitivity of liquid based cytology with conventional Pap smear. METHODOLOGY: This study was carried out on 100 randomly selected women of aged 21- 60 years who presented with symptoms of vaginal discharge, lower abdomen pain, post coital bleeding, irregular periods and with cervical lesion from the Gynaecology outpatient department at CMCH between June 2011 – June 2012. Specimen was collected for both conventional pap smear and liquid based cytology then colposcopic guided biopsy was performed in all 100 cases. By using biopsy proven CIN cases as the gold standard the sensitivity of both the cytology method was obtained. Comparative study of Liquid Based Cytology and Pap smear in Cancer cervix screening RESULTS: In our study LBC showed abnormality in 32 cases and in Pap smear it was in 17 cases. The rate of Unsatisfactory smear was low in LBC than Pap smear (1% vs 6%). The rate of prediction of infectious agent was more with LBC (14%) than Pap smear (3%). It is noted that Low grade squamous intraepithelial lesion (16%) and High grade squamous intraepithelial lesion (10%) prediction was more with LBC than Pap smear (LSIL 5%, HSIL 1%) and it was statistically significant. The prediction of Atypical Squamous cell (ASC) category was more with Pap smear than LBC (8% vs 2%).The false negative rate of Pap smear was more than LBC (49% vs 3%).The sensitivity for detection of a histologically proven lesion is significantly higher in LBC compared to Conventional Pap smear(96% vs 51%). CONCLUSION: It is inferred from this study on comparing LBC with Conventional Pap smear relative to histology, Liquid Based Cytology is better than Conventional Pap test in detecting preinvasive cervical lesions. Liquid Based Cytology showed increased sensitivity for the prediction of cytologic abnormality and decreased false negative rate compared to Pap tests.