HPV HANDBOOK - Zervita

CERVICAL CYTOLOGY AS A SCREENING TESTKey elements of cervical cancer screening• Population coverage of all social classes• Target age range• Compliance• Screening interval• Sample taking and handling• Cytological analysis and reporting of results• Patient follow-up and treatment of pre-cancerous lesions• Quality control and audit procedures that cover all aspects ofthe programme, from invitation to post-treatment follow-upjudgement of the individuals who are interpreting the tests, as well asthe selection of the particular cut-off points that are used to define apositive or negative result.It has been estimated that the sensitivity of Pap smears can rangefrom 50% to 70%. 13–15 Consequently, approximately 30–50% ofhistologically confirmed pre-cancerous lesions would not be detectedby a single Pap smear. However, the sensitivity of the Pap smear forthe detection of high-grade lesions is greater than that for low-gradelesions. Conversely, the Pap smear is less sensitive for the detectionof adenocarcinoma than for squamous cell carcinoma. 7,16The specificity of the Pap smear test usually ranges from 95% to99.5%, this variation being largely dependent on whether the cut-offfor a positive test result is set at the need for follow-up or the need forimmediate treatment (i.e. referral to colposcopy for high-gradedisease). Using the need for immediate treatment as the threshold, thespecificity of the Pap smear within the Finnish cervical cancerscreening programme is high. In Finland, the overall frequency ofreferral for colposcopy or other confirmatory investigations is