A study has assessed whether the increased sensitivity of screening for human papillomavirus ( HPV ) may represent overdiagnosis and to compare the long term duration of protective effect against cervical intraepithelial neoplasia grade 2 or worse ( CIN2+ ) in HPV based and cytology based screening.
13 year follow-up data of the Swedescreen randomised controlled trial of primary HPV screening were presented.
12 527 women aged 32-38 attending organised screening were enrolled and randomised to HPV and cytology double testing ( intervention arm, n=6257 ) or to cytology only, with samples frozen for future HPV testing ( control arm, n=6270 ).
The main outcome measure was cumulative incidence of CIN2+ and CIN3+ ( Kaplan Meier curves ).
The increased detection of CIN2+ in the intervention arm decreased over time.
After six years, the cumulative incidence of CIN3+ was similar in both trial arms, and after 11 years the cumulative incidence of CIN2+ became similar in both arms.
The longitudinal sensitivity of cytology for CIN2+ in the control arm at three years was similar to the sensitivity of HPV testing in the intervention arm at five years of follow-up: 85.94% ( 95% confidence interval 76.85% to 91.84% ) vs 86.40% ( 79.21% to 91.37% ).
The sensitivity of HPV screening for CIN3+after five years was 89.34% ( 80.10% to 94.58% ) and for cytology after three years was 92.02% ( 80.59% to 96.97% ).
In conclusion, over long term follow-up, the cumulative incidence of CIN2+ was the same for HPV screening and for cytology, implying that the increased sensitivity of HPV screening for CIN2+ reflects earlier detection rather than overdiagnosis.
The low long term risks of CIN3+ among women who tested negative in HPV screening, support screening intervals of five years for such women. ( Xagena )
Elfström KM et al, BMJ 2014;348:g130