Comparison of HPV test versus conventional and automation-assisted Pap screening as potential screening tools for preventing cervical cancer

Objective To evaluate new techniques in primary cervical cancer screening programmes. Design Cross sectional pilot study. Setting Department of Obstetrics and Gynaecology, Helsinki University Hospital. Population Consecutive 2032 human papillomavirus (HPV) DNA and Pap smear samples were taken. Histological diagnoses were obtained from 460 patients. Methods We compared the validity of the high risk (HR) HPV DNA detection test to automation-assisted and conventional Pap smear screening. Main outcome measures Specificity and sensitivity of screening methods. Results Twenty-three percent of women were HPV positive. Forty-five of 46 had high grade lesions and cancers were HR HPV DNA positive, whereas 72/93 of low grade and more severe lesions were HR HPV DNA positive. When histologically verified high grade lesions were observed, the relative sensitivity of HR Hybrid Capture 2 (HR HC2) test was 98% compared with conventional Pap smear and Papnet tests, which performed 54% versus 58%, 83% versus 86% and 93% versus 98% relative sensitivity respectively, using cytological diagnoses HSIL (high grade squamous intraepithelial lesion), LSIL (low grade squamous intraepithelial lesion) or ASCUS (atypical squamous cells of undetermined significance) as the cutoff. The specificity of HC2 test (77-79%) was comparable with the ASCUS+ (ASCUS and more severe) cytology (68-79%), but lower when compared with LSIL+ (91-95%) or especially HSIL+ (97-99%) Pap smear results. Conclusion Pap smear, as a screening test, is very different from HPV DNA detecting test HR HC 2. If cutoff LSIL or more severe lesions is used, primary Pap smear is clearly more specific than HR HC2, but markedly less sensitive. Due to high relative sensitivity of the HPV, only very few histologically confirmed high grade lesions would be detected among HPV negatives using simultaneous cytology. On the other hand, using HPV DNA test alone would lead to multifold amounts of referrals for colposcopy. A posterior Pap smear assessment among HPV positives might be helpful in increasing sensitivity and specificity of screening and defining those who need an immediate referral or treatment. We plan to incorporate primary HR HPV DNA test with posterior Pap smear reading of HPV positives into our ongoing randomised prospective multiarm trial evaluating new techniques in organised screening for cervical cancer in Finland.