Diagnostic performance of p16/Ki-67 dual immunostaining at different number of positive cells in cervical smears in women referred for colposcopy

Background

The aim of the study was to evaluate the diagnostic accuracy of p16/Ki-67 dual immunostaining (p16/ Ki-67 DS) in cervical cytology and the number of positive p16/Ki-67 cells to diagnose high grade cervical intraepithelial neoplasia (CIN2+) in colposcopy population.

Subjects and methods

We performed an analysis on a subset cohort of 174 women enrolled within a large-scale randomised controlled human papillomavirus (HPV) self-sampling project organised as part of the population-based Cervical Cancer Screening Programme ZORA in Slovenia. This subset cohort of patients was invited to the colposcopy clinic, underwent p16/Ki-67 DS cervical cytology and had the number of p16/Ki-67 positive cells determined.

Results

Among analysed women, 42/174 (24.1%) had histologically confirmed CIN2+. The risk for CIN2+ was increasing with the number of positive cells (p < 0.001). The sensitivity of p16/Ki-67 DS for detection of CIN2+ was 88.1%, specificity was 65.2%, positive predictive value was 44.6% and negative predictive value was 94.5%.

Conclusions

Dual p16/Ki-67 immunostaining for the detection of CIN2+ has shown high sensitivity and high negative predictive value in our study, which is comparable to available published data. The number of p16/Ki-67 positive cells was significantly associated with the probability of CIN2+ detection. We observed a statistically significant and clinically relevant increase in specificity if the cut-off for a positive test was shifted from one cell to three cells.

Association of p16 and Ki-67 with Risk of Recurrence in Previously Treated Cervical High-Grade Squamous Intraepithelial Lesions

OBJECTIVE

Our main objective was to assess the association between the markers p16 and Ki-67 and recurrence of disease in patients previously treated for cervical high-grade squamous intraepithelial lesion (HSIL).

DESIGN

This is a case-control study at the National Cancer Institute conducted between 2005 and 2015. Of the patients with a pathologically confirmed diagnosis of HSIL, 107 cases were selected. They were divided into 2 groups: 28 cases with recurrence after treatment and a control group of 79 patients without recurrence. We identified clinical, pathological, and treatment variables.

METHODS

Two experienced pathologists performed immunohistochemical analysis of biomarkers; they agreed on their interpretation, and we calculated the odds ratios (ORs) associated with recurrence. For group comparisons, we used the Wilcoxon signed-rank, χ2, or Fisher's exact test, depending on the type of variable. We conducted logistic regression models to estimate ORs and determine the factors associated with recurrence. The recurrence-free period was defined as the time frame between conization and either recurrence of disease or the last date the patient was seen. We used Kaplan-Meier plots to visualize survival curves and log-rank tests to compare the curves. We established a p value <0.05 as statistically significant.

RESULTS

After pathologists performed immunohistochemical analysis, they achieved an agreement level of 83.7% for p16 and 60% for Ki-67. We did not find an association between recurrence and either p16 expression (p = 0.69) or the percentage of Ki-67 expression (p = 0.71). The recurrence-free period analysis did not reveal a difference in p16 expression (p = 0.57) nor in the percentage of Ki-67 expression in the 3-tiered scale (p = 0.56).

LIMITATIONS

Our main limitation was a reduced sample size.

CONCLUSION

We found no association between p16 and Ki-67 positivity and the risk of recurrence in previously treated HSIL.

Role of p16/Ki-67 Dual Immunostaining in Detection of Cervical Cancer Precursors

Background

Pap-smears-based cytology and human papilloma virus testing have their own limitations in detecting cervical precancerous lesions, and still need further standardization. Co-expression of p16^ink4a and Ki-67 can be used as additional biomarker.

Aims

To study the role of liquid-based cytology and the dual immunostaining for p16/Ki-67 in predicting the presence of significant lesion in cases of mild cytological atypia.

Materials and Methods

A prospective, cross-sectional study was performed in the Department of Pathology, in collaboration with Department of Obstetrics and Gynecology over 15 months including 545 patients. Immunocytochemistry followed by colposcopy-guided biopsy were performed in 52 cases with epithelial abnormalities.

Results

Thirty-five cases (67%) were dual-stain positive among the cases with epithelial abnormalities. In the ASC-US and LSIL group, the sensitivity and specificity of the immunostaining in diagnosing CIN2+ lesions were 100 and 70% and 87.5 and 100%, respectively. p16/Ki-67 positivity also increased with cytological severity which in turn corresponded with histological findings: it reached from 33% in ASC-US to 100% in both HSIL and SCC categories.

Conclusion

This dual immunostaining may potentially be a useful tool in the triage of the ASC-US and the LSIL group, considering the high sensitivity and specificity values.