Human papillomavirus infection in women who develop high-grade cervical intraepithelial neoplasia or cervical cancer: a case-control study in the UK.

Human papillomavirus (HPV) testing might identify older women who could be withdrawn from the cervical screening programme, or require less frequent screening. A case-control study using the United Kingdom cervical screening population was set up to help address this issue. Cases comprised 575 women who developed cervical intraepithelial neoplasia (CIN) grade 2 or worse over a 13-year period following a cytologically normal baseline smear, and were stratified by age group ('under 20', '20-39' and 40 years or over). Controls (n=601) were women who remained disease free over this interval and were the same age on average as cases. DNA was extracted from the baseline smears and tested for HPV by PCR using GP5+/6+ consensus primers. HPV+ samples were tested for HPV types 16 and 18 using specific PCR primers. In all, 27.0% of cases tested positive for HPV at baseline, compared with 15.4% of controls (odds ratio (OR)=2.00; 95% confidence interval (CI), 1.50-2.68). Among women aged 40 years or over, the OR for HPV 16 was 8.95 (95% CI, 2.63-30.4). These results support the need for further cervical screening of HPV- older women, as many of the cases were HPV- at baseline.