Effect of Several Negative Rounds of Human Papillomavirus and Cytology Co-testing on Safety Against Cervical Cancer

Background: Current U.S. cervical cancer screening and management guidelines do not consider previous screening history, because data on multiple-round human papillomavirus (HPV) and cytology "co-testing" have been unavailable. Objective: To measure cervical cancer risk in routine practice after successive negative screening co-tests at 3-year intervals. Design: Observational cohort study. Setting: Integrated health care system (Kaiser Permanente Northern California, Oakland, California). Patients: 990 013 women who had 1 or more co-tests from 2003 to 2014. Measurements: 3- and 5-year cumulative detection of (risk for) cervical intraepithelial neoplasia grade 3, adenocarcinoma in situ, and cervical cancer (≥CIN3) in women with different numbers of negative co-tests, overall and within subgroups defined by previous co-test results or baseline age. Results: Five-year ≥CIN3 risks decreased after each successive negative co-test screening round (0.098%, 0.052%, and 0.035%). Five-year ≥CIN3 risks for an HPV-negative co-test, regardless of the cytology result, nearly matched the performance (reassurance) of a negative co-test for each successive round of screening (0.114%, 0.061%, and 0.041%). By comparison, ≥CIN3 risks for the cytology-negative co-test, regardless of the HPV result, also decreased with each successive round, but 3-year risks were as high as 5-year risks after an HPV-negative co-test (0.199%, 0.065%, and 0.043%). No interval cervical cancer cases were diagnosed after the second negative co-test. Independently, ≥CIN3 risks decreased with age. Length of previous screening interval did not influence future ≥CIN3 risks. Limitation: Interval-censored observational data. Conclusion: After 1 or more negative cervical co-tests (or HPV tests), longer screening intervals (every 5 years or more) might be feasible and safe. Primary Funding Source: National Cancer Institute Intramural Research Program.