Risk of cervical intraepithelial neoplasia grade 3 or higher (CIN3+) among women with HPV-test in 1990–1992, a 30-year follow-up study

Background/objective - Having a 30-year follow-up of a cohort of women tested for HPV is a unique opportunity to further study long-term risk of CIN3+. The study objective was to compare HPV status at baseline with the risk of CIN3+ in the follow-up period of 30 years. Methods - All women (n = 642) referred to the HPV outpatient clinic at the University Hospital of North Norway (UNN) in 1990–1992, with an HPV test at baseline, were included in a prospective cohort. HPV-testing was performed by two different HPV-DNA tests, and genotypes 6, 11, 16, 18, 31 and 33 were identified. High-risk (HR) HPV genotypes (16, 18, 31 and 33) were classified as HPV positive, whereas low-risk (LR) genotypes (6 and 11) in addition to absent HPV were classified as HPV negative. A single cohort in which women were classified for their HPV status underwent follow-up prospectively to the last time-point of observation of 30 years. Results - During follow-up, 148 (148/642) cases of CIN3+ were detected, of whom 70.3% (104/148) were HPV positive and 29.7% (44/148) were HPV negative at baseline. The proportions of women who developed CIN3+ following a positive and a negative test were 46.6% (104/223) and 10.5% (44/419), respectively. Most cases of CIN3+ were seen shortly after the baseline HPV test, with 112 cases of CIN3+ diagnosed within the first year. In total, 48.6% (72/148) with HPV 16 and 57.6% (19/33) with HPV 33 developed CIN3+. Within the first year, CIN3+ was detected in 37.8% (56/148) with HPV 16, and 51.5% (17/33) with HPV 33. The long-term risk of CIN3+ was significantly lower than the short-term risk, and mainly associated with HPV 16. Overall, eight cases of cervical cancer were detected. Five were HPV positive, harboured HPV 16 at baseline and developed cervical cancer after 3, 4, 5, 11 and 24 years of follow-up. Conclusion and consequences - HPV status at baseline is predictive for the subsequent risk of developing CIN3+. Women with a positive HPV test in 1990–1992 had a significantly higher risk of CIN3+ during 30 years of follow-up than those with a negative test. HPV 16 was associated with the greatest long-term risk of cervical cancer. All patients with a positive HPV test at baseline should be followed up until negative