Role of pap-test in cervical cancer prevention: a systematic review and meta-analysisBrigid Unim

Background Cervical cancer is third in incidence and fourth in mortality among cancers of women worldwide. Screening-test, such as conventional cytology, are used to identify pre-cancers, to prevent the occurrence of invasive cancers or to diagnose an early stage of disease, permitting a well-timed treatment. This systematic review and meta-analysis investigates the effective- ness of pap test in the prevention of cervical cancer. Methods A systematic review and meta-analysis were performed. The literature review, from 1979 to 2013, was based on Pubmed, Scopus, Google Scholar and ISI engines using the keywords ‘‘pap test AND study design (RCT, cohort, case-control, cross sectional) AND cervical cancer’’. The selection of articles was carried out independently by four authors. Predefined study quality indicators were applied for evaluation of articles: Jadad scale was used for randomized clinical trials (RCTs) and New Castle-Ottawa Scale for other studies. Four different meta- analyses were carried out, one for each study design, using the RevMan software version 5 for Windows. Results From the 3372 screened citations, 360 met our inclusion criteria (86 cohort, 119 RCT, 62 cross-sectional and 93 case- control). All papers were selected for title, abstract and study design pertinence. Up to 81 doublets, 871 cohort, 526 RCT, 1046 cross sectional and 669 case-control studies were excluded. Meta-analysis shows that Pap test reduces mortality from and incidence of advanced cervical cancer compared to no screening [mortality risk ratio (RR) 0.65, 95% CI 0.47-0.90; incidence RR 0.56, 95% CI 0.42-0.7]. In a cohort study pap test reduced the risk of invasive cervical cancer diagnosis compared to no screening (RR 0.38, 95% CI = 0.23-0.63. Furthermore, a history of two negative Pap test rather than one is associated with a decreased risk of developing cancer of the cervix (OR 1.33, 95% CI 0.93-1.90 vs OR 1.55, 95% CI 1.15-2.10). Conclusions Pap test is an effective screening tool, it is protective and associated with a reduced risk of incidence of and mortality for advanced cervical cancer. Risk-relative should be stratified for women’s age, ethnic group, number of previous pap smears, and time of follow-up. Key messages - Cytological screening programs play a major role in reducing both incidence and mortality of invasive cervical cancers. - The importance of Pap-test in early diagnosis of cervical can- cer remains unaltered despite the availability of new screen- ing methods, different HPV-DNA tests and HPV vaccines.