Detection rates of precancerous and cancerous cervical lesions within one screening round of primary human papillomavirus DNA testing: prospective randomised trial in Finland

OBJECTIVE To compare the detection rates of precancerous and cancerous cervical lesions by human papillomavirus (HPV) DNA testing and by conventional cytology screening. DESIGN Prospective randomised trial. Two cohorts were followed over one screening round of five years, screened initially by primary HPV DNA testing or by primary Pap test. SETTING Population based programme for cervical cancer screening in Finland. PARTICIPANTS Women aged 25-65 years invited for screening in 2003-07 (101,678 in HPV arm; 101,747 in conventional cytology arm). INTERVENTION Women were randomly allocated (1:1) to primary HPV DNA screening followed by cytology triage if they had positive results, or to primary cytology screening. Screening method was disclosed at the screening visit. Trial personnel involved were aware of all test results. MAIN OUTCOME MEASURES Cumulative detection rates of cervical intraepithelial neoplasia (CIN), adenocarcinoma in situ (AIS), and invasive cervical cancer before the second screening (after five years) or before 31 December 2008. Lesions detected at screening and during the five year interval were included. RESULTS 1010 and 701 precancerous or cancerous lesions were detected during an average follow-up of 3.6 years in the HPV and cytology arms, respectively. Among invited women, the hazard ratio was 1.53 (95% confidence interval l.28 to 1.84) for CIN grade 1, 1.54 (1.33 to 1.78) for CIN 2, 1.32 (1.09 to 1.59) for CIN 3 or AIS, and 0.81 (0.48 to 1.37) for cervical cancer. In 25-34 year old participants, the cumulative hazard (or cumulative detection rate) was 0.0057 (0.0045 to 0.0072) for HPV screening versus 0.0046 (0.0035 to 0.0059) for conventional screening; corresponding data for women aged 35 years and older were 0.0022 (0.0019 to 0.0026) and 0.0017 (0.0014 to 0.0021), respectively. CONCLUSIONS Primary HPV DNA screening detects more cervical lesions than primary cytology within one screening round of five years. Even if the detection rate of CIN 3 or AIS increased in the HPV arm in both age groups, the absolute difference in cumulative rates in women aged 35 years or older was small. By carefully selecting age groups and screening intervals, HPV screening could increase the overall detection rate of cervical precancerous lesions only slightly. However, these findings should be interpreted in the context of the high level of opportunistic screening that occurs in Finland. TRIAL REGISTRATION International Standard Randomised Controlled Trial ISRCTN23885553.