Use of p16-INK4A overexpression to increase the specificity of human papillomavirus testing: a nested substudy of the NTCC randomised controlled trial.

BACKGROUND: Human-papillomavirus (HPV) testing is more sensitive, but less specific, than conventional cytology for detecting high-grade cervical intraepithelial neoplasia (CIN). We assessed whether HPV testing with triage by p16-INK4A overexpression can increase specificity while maintaining sensitivity. METHODS: HPV-positive women were enrolled between June 10, 2003, and Dec 31, 2004 in a multicentre randomised controlled trial, which compared stand-alone HPV testing by Hybrid Capture 2 (experimental group) with conventional cytology, were referred for colposcopy. In seven of nine centres, cytospin preparations from these women were tested for p16-INK4A overexpression by immunostaining. The sensitivity and specificity for CIN grade 2 or more, determined at blind review of histology, were calculated for these women. We also estimated the relative sensitivity and relative referral to colposcopy that would have been obtained by HPV testing with p16-INK4A triage compared with conventional cytology. This trial is registered as a Standard Randomised Controlled Trial, number ISRCTN81678807. FINDINGS: 24 661 women were randomly assigned to the experimental group. 1137 women (74% of those undergoing colposcopy in relevant centres), including 50 with CIN2 and 42 with CIN3 or cancer, had valid p16-INK4A immunostaining. For the endpoint of CIN2+, sensitivity and specificity of p16-INK4A (deemed positive with any number of stained cells-except endocervical, metaplastic, and atrophic cells if morphologically normal) in HPV-positive women of any age were 88% (81 of 92; 95% CI 80-94) and 61% (633 of 1045; 57-64), respectively. In the 35-60-year age group, the relative sensitivity of HPV testing and p16-INK4A triage versus conventional cytology for CIN2+ was 1.53 (95% CI 1.15-2.02) and relative referral was 1.08 (0.96-1.21). In the 25-34-year age group, relative sensitivity was 3.01 (1.82-5.17) and relative referral was 1.15 (0.96-1.37). In the latter age group, when 5% or more stained cells were deemed positive, the corresponding values were 2.06 (1.20-3.68) and 0.58 (0.46-0.73), respectively. INTERPRETATION: HPV testing with p16-INK4A triage produces a significant increase in sensitivity compared with conventional cytology, with no substantial increase in referral to colposcopy.

Accuracy of liquid based versus conventional cytology: overall results of new technologies for cervical cancer screening: randomised controlled trial.

OBJECTIVE: To compare the accuracy of conventional cytology with liquid based cytology for primary screening of cervical cancer. DESIGN: Randomised controlled trial. SETTING: Nine screening programmes in Italy. PARTICIPANTS: Women aged 25-60 attending for a new screening round: 22 466 were assigned to the conventional arm and 22 708 were assigned to the experimental arm. INTERVENTIONS: Conventional cytology compared with liquid based cytology and testing for human papillomavirus. MAIN OUTCOME MEASURE: Relative sensitivity for cervical intraepithelial neoplasia of grade 2 or more at blindly reviewed histology, with atypical cells of undetermined significance or more severe cytology considered a positive result. RESULTS: In an intention to screen analysis liquid based cytology showed no significant increase in sensitivity for cervical intraepithelial neoplasia of grade 2 or more (relative sensitivity 1.17, 95% confidence interval 0.87 to 1.56) whereas the positive predictive value was reduced (relative positive predictive value v conventional cytology 0.58, 0.44 to 0.77). Liquid based cytology detected more lesions of grade 1 or more (relative sensitivity 1.68, 1.40 to 2.02), with a larger increase among women aged 25-34 (P for heterogeneity 0.0006), but did not detect more lesions of grade 3 or more (relative sensitivity 0.84, 0.56 to 1.25). Results were similar when only low grade intraepithelial lesions or more severe cytology were considered a positive result. No evidence was found of heterogeneity between centres or of improvement with increasing time from start of the study. The relative frequency of women with at least one unsatisfactory result was lower with liquid based cytology (0.62, 0.56 to 0.69). CONCLUSION: Liquid based cytology showed no statistically significant difference in sensitivity to conventional cytology for detection of cervical intraepithelial neoplasia of grade 2 or more. More positive results were found, however, leading to a lower positive predictive value. A large reduction in unsatisfactory smears was evident. TRIAL REGISTRATION: Current Controlled Trials ISRCTN81678807 [controlled-trials.com].