Evaluation of Sensitivity and Specificity of Pap Smear, LBC and HPV in Screening of Cervical Cancer

Abstract

Cervical cancer ranks as the fourth leading cause of female cancer in the world, and it is the second most common female cancer in women aged 15–44 years. Strict implementation of screening programs has led to a large decline in cervical cancer incidence and mortality in developed countries. In contrast, cervical cancer remains largely uncontrolled in high-risk developing countries because of ineffective or no screening. Conventional Pap smear method has been the mainstay of most of the screening programs since decades. However, this technique is not without limitations and the sensitivity and specificity of cervical cytology are relatively low. To overcome the limitations of conventional Pap smear, liquid-based cytology was introduced in 1990s as a better tool for processing cervical samples. HPV testing alone or with cytology triage is currently increasingly being used as a primary screening approach for cervical neoplasia. The present study was undertaken to evaluate sensitivity and specificity of conventional Pap smear, liquid-based cytology and HPV DNA in our setting. This study was conducted in Gynecological Oncology unit at Indira Gandhi Institute of Medical Sciences, Patna, Bihar. In total, 1500 women were enrolled in this study and sample was taken for conventional cytology, liquid-based cytology and HPV DNA. The smears were studied in detail and were interpreted as per the Bethesda system of reporting Pap smears. The results were compared and analyzed statistically. Approximately 5% patients having epithelial cell abnormalities on Pap smear, 5.33% on LBC and 6.86% had abnormal report on HPV DNA testing. Unsatisfactory smears were more commonly reported by conventional method (7.2%) than by liquid-based method (1.62%), and this difference is statistically significant. There was no difference in the detection of epithelial cell abnormalities by both the methods. Sensitivity of Pap smear, LBC and HPV DNA was 75.80%, 76.47% and 89.89%, respectively. Specificity of Pap smear, LBC and HPV DNA was 98.05%, 98.93 and 98.00%, respectively. LBC has been found to be more superior to conventional smears only with respect to lesser number of unsatisfactory smears.