Improved abnormal Pap smear triage using cervical cancer biomarkers.

OBJECTIVE: The current system of Pap smear screening and management of abnormal cytology has resulted in a marked reduction in invasive cervical cancer. Many women, however, are not found to have significant precursor lesions. This is due to the poor specificity of high-risk human papillomavirus (HPV) triage. More specific cervical cancer biomarkers may be more effective triage tools than hr-HPV. We evaluated whether a dual stain for p16 and Ki-67 might improve the triage of abnormal Pap smears. MATERIALS AND METHODS: p16/Ki-67 immunostaining was performed on additional slides prepared from 515 women with abnormal Pap smears (301 atypical squamous cells of undetermined significance [ASCUS], 169 low-grade squamous intraepithelial lesion [LSIL], 29 atypical squamous cells-cannot exclude high-grade lesion [ASC-H], 16 high-grade squamous intraepithelial lesion [HSIL]). High-risk HPV typing was performed on all cases. Immunostaining and hr-HPV were compared in relation to their diagnostic accuracy for the detection of biopsy-proven cervical intraepithelial neoplasia (CIN) 2/3. A cost analysis comparing hr-HPV versus immunostaining as the initial triage tool used for abnormal Pap smears was also performed. RESULTS: High-risk HPV was positive in 127 (42.2%) ASCUS, 129 (76.3%) LSIL, 20 (69.0%) ASC-H, and 15 (93.8%) HSIL. p16/Ki-67 was positive in 54 (17.9%) ASCUS, 73 (43.2%) LSIL, 19 (65.5%) ASC-H, and 15 (93.8%) HSIL. For detection of CIN 2/3, sensitivity/specificity of hr-HPV and p16/Ki-67 was 89.29%/14.94% and 96.43%/60.92%, respectively. Overall, diagnostic accuracy was statistically significantly higher for p16/Ki-67 compared with hr-HPV. Compared to HPV, immunostain triage could have generated approximately $46,000 savings in the study population. CONCLUSIONS: The triage of abnormal Pap smears by p16/Ki-67 immunostaining shows comparable sensitivity, improved specificity, and significantly improved diagnostic performance when compared to hr-HPV. Immunostaining is of value in triaging LSIL and ASC-H Pap smears in addition to ASCUS. The widespread utilization of biomarker triage could result in significant health care cost savings without compromising the detection of significant cervical cancer precursors.

Can we improve the positive predictive value of atypical glandular cells not otherwise specified?

The category of atypical glandular cells (AGC) in gynecologic cytopathology presents many well-documented diagnostic challenges, the most significant related to high interobserver variability, low specificity, and low positive predictive value. The current Bethesda System provides criteria for specific glandular categories including atypical endocervical cells not otherwise specified (AEC-NOS), AEC favor neoplastic, and atypical endometrial cells. The Bethesda System does, however, acknowledge that in some cases AGC cannot be categorized based upon cell of origin, in which case the generic term "atypical glandular cells" (AGC) may be used. We sought to determine whether further refinement of the current Bethesda System criteria for AEC-NOS might increase the positive predictive value of the general category of AGC. Fifty-three cases of AGC with documented histologic follow-up at the University of Illinois Hospital were reviewed. The cases were graded on each of the eight specific cytologic criteria recommended by the current Bethesda System for AEC-NOS using a study-developed three-tier grading system. Multiple regression analysis showed that four of the cytologic criteria in combination--nuclear enlargement, nuclear pleomorphism, increased nuclear-to-cytoplasmic (N/C) ratio, and cells occurring in sheets and strips with cell crowding and nuclear overlap--discriminated positive histologic outcome slightly better than any single criterion alone. In addition, simple logistic regression analysis showed nuclear enlargement to have a marginal independent association with positive histologic outcome (P = 0.0566). No other criterion was independently associated with outcome. Ancillary methods seem indicated to increase the positive predictive value of AGC at this time.