The risk of false-positive histology according to the reason for colposcopy referral in cervical cancer screening: a blind revision of all histologic lesions found in the NTCC trial.

All cervical intraepithelial neoplasia (CIN) diagnoses identified during the New Technologies for Cervical Cancer trial (ISRCTN81678807) were blindly reviewed by 2 pathologists. Original diagnoses based on colposcopy-guided biopsies were compared with those made by the reviewers who had access to all clinical histologic samples (including postsurgical). Cases downgraded from CIN 2+ by the reviewers were considered indicative of unnecessary treatments. The analyses are presented according to the molecular (high-risk human papillomavirus [HPV]) and/or cytologic diagnosis used to refer the women for colposcopy. We reviewed 812 CIN 1 and 364 CIN 2 + diagnoses. The specificity of colposcopy-guided biopsy was 98% and the sensitivity, 84%. The probability of unnecessary treatment was 27% for women with atypical squamous cells of undetermined significance cytologic findings and 8% for women with low-grade squamous intraepithelial lesion or worse, 10% for HPV+ and positive cytologic findings, and 16% for HPV+ alone. The positive predictive value of the first-level screening test was inversely associated with probability of a histologic false-positive result (P = .015). In screening, a low positive predictive value of the colposcopy-referring test may result in unnecessary treatments.