The IMPACT trial: human papillomavirus, cervical cytology and histopathological results from the baseline and 1-year follow-up phase.

Abstract Background An increase in human papillomavirus (HPV) test volumes is expected in the near future as HPV–based screening protocols are expected to become more broadly adopted. Objective The IM proving P rimary screening A nd C olposcopy T riage (IMPACT) trial, a prospective, multicenter US cervical cancer screening trial, was conducted to obtain FDA approvals for the new high-throughput cobas HPV for use on the cobas 6800/8800 Systems (cobas HPV) for detecting cervical precancer and cancer (cervical intraepithelial neoplasia of grade 2 or worse [≥CIN2] and grade 3 or worse, [≥CIN3]). Here the baseline demographics, HPV, cervical cytology and histolpathologic results are presented. Additionally the baseline and 1-years risks of ≥CIN2 and ≥CIN3 associated with HPV results are reported. Study design In total, 35,263 women aged 25–65 years undergoing routine screening were enrolled; liquid-based cytology and 2 high-risk HPV PCR-based tests were performed. Women with abnormal Pap cytology, women positive for high-risk HPV by either of the two HPV tests, and a random subset of women negative by Pap cytology and the 2 HPV tests were referred to colposcopy/cervical biopsy. Women who did not meet the study endpoint were eligible for the 1-year follow-up study phase. Verification bias–adjusted cervical disease prevalence and risks and 95% confidence intervals were computed. Results The prevalence of ASC-US and >ASC-US cytology were 6.5% and 3.2%, respectively. Prevalence of high-risk HPV, HPV16, and HPV18 base on the new cobas HPV test were 15.1%, 3.1%, and 1.4%, respectively. Both cytologic abnormalities and HPV positivity declined with increasing age. Among women who had a colposcopy/biopsy, prevalence of ≥CIN2 and ≥CIN3 were 8.8% and 3.6%, respectively. The baseline and 1-year cumulative risks for ≥CIN3 were 13.6% and 16.9%, respectively, in HPV16-postive women. HPV-negative women had the lowest 1-year cumulative risk for ≥CIN3 (0.06%). Conclusion The contemporary age-specific prevalence of HPV (including HPV16 and HPV18), cytologic abnormalities, and CIN in a large U.S. cervical cancer screening population provides benchmarks for health care policy, screening programs, and for laboratories and clinicians.