Intra- and inter-observer reproducibility of CINtec® PLUS in ThinPrep® cytology preparations

Triaging HPV-Positive Cervical Samples with p16 and Ki-67 Dual Stained Cytology within an Organized Screening Program-A Prospective Observational Study from Western Norway

The implementation of high-risk human papillomavirus testing (hrHPV testing) as a screening method in substitute for cytology has evoked the need for more sensitive and less objective tests for the triage of HPV-positive women. In a cohort of 1763 HPV-positive women, the potential of immunocytochemical p16 and Ki-67 dual staining as compared to cytology, alone or in combination with HPV partial genotyping, was tested for triage of women attending a cervical cancer screening program. Performance was measured using sensitivity, specificity, and positive and negative predictive values. Comparisons were assessed using logistic regression models and the McNemar test. Dual staining was evaluated in a prospectively collected study cohort of 1763 HPV-screened women. For triage of CIN2+ and CIN3+, NPV and sensitivity, 91.8% and 94.2% versus 87.9% and 89.7%, respectively, were significantly higher using dual staining together with HPV 16/18 positive, as compared to cytology (p < 0.001). The specificities, however, were lower for dual staining as compared to cytology. Conclusions: Dual staining is safer for decision-making regarding HPV-positive women's need for follow-up with colposcopy and biopsy, as compared to cytology.

Quality Control of Biospecimens in a Danish Clinical Cytology Biobank

Introduction: Based on the experience from a Swedish biobank, we established a clinical cervical cytology biobank and adapted it to a Danish setting. The aim of the present study was to validate the biobank material regarding quality and quantity, to determine the usefulness of the material for future diagnostics and biomarker testing. Methods: Cervical cytology samples collected in ThinPrep were analyzed before and after biobanking using p16/ki-67 dual staining, a human papillomavirus (HPV) DNA test (Cobas), and a test for HPV messenger RNA (mRNA; Aptima). The concordance of the test results before and after biobanking was assessed. We also evaluated the morphology before and after biobanking and did additional tests on the biobanked material to qualify the usefulness of the material (library preparation for next-generation sequencing [NGS], reverse transcription-polymerase chain reaction [RT-PCR], and the Inno-Lipa HPV genotyping test). Results: For the Cobas HPV test, the concordance was 92% (122/133), and for the Inno-Lipa test (30 samples), it was 100%. For the Aptima assay, the concordance was a little lower, 84% (42/50). The morphology of the cell was well preserved, and the concordance of the p16/ki-67 dual staining was 88% (37/42). The functional tests showed that DNA-based NGS libraries (TST15 panel; Illumina) had good quality parameters. However, with the RT-PCR, 12% of the samples showed poor quality and a too low input amount for the analysis. Conclusion: The quality of the biobanked samples is high, and the material is suitable for testing of DNA, RNA, and protein. However, for testing of specific biomarkers, pilot studies are recommended to ensure sufficient input amount and quality of the material, especially for RNA-based studies.

False Negative Results in Cervical Cancer Screening-Risks, Reasons and Implications for Clinical Practice and Public Health

False negative (FN) results in cervical cancer (CC) screening pose serious risks to women. We present a comprehensive literature review on the risks and reasons of obtaining the FN results of primary CC screening tests and triage methods and discuss their clinical and public health impact and implications. Misinterpretation or true lack of abnormalities on a slide are the reasons of FN results in cytology and p16/Ki-67 dual-staining. For high-risk human papillomavirus (HPV) molecular tests, those include: truly non-HPV-associated tumors, lesions driven by low-risk HPV types, and clearance of HPV genetic material before sampling. Imprecise disease threshold definition lead to FN results in visual inspection with acetic acid. Lesions with a discrete colposcopic appearance are a source of FN in colposcopic procedures. For FAM19A4 and hsa-miR124-2 genes methylation, those may originate from borderline methylation levels. Histological misinterpretation, sampling, and laboratory errors also play a role in all types of CC screening, as well as reproducibility issue, especially in methods based on human-eye evaluation. Primary HPV-based screening combined with high quality-assured immunocytochemical and molecular triage methods seem to be an optimal approach. Colposcopy with histological evaluation remains the gold standard for diagnosis but requires quality protocols and assurance measures.

Determinants of p16/Ki-67 adequacy and positivity in HPV-positive women from a screening population

BACKGROUND

The objective of this study was to describe the determinants of adequacy and positivity of the p16/Ki-67 assay in a human papillomavirus (HPV)-positive screening population enrolled within the New Technologies for Cervical Cancer 2 (NTCC2) study.

METHODS

ThinPrep slides were immunostained for p16/Ki-67; each slide had 3 reports from different laboratories. The authors included population-related, sampling-related/staining-related, and interpretation-related variables in the analyses. Adequacy and positivity proportions were stratified by variables of interest. Univariate and multivariate logistic models were used to identify determinants of adequacy and positivity.

RESULTS

In total, 3100 consecutive HPV-positive cases were analyzed. Because every slide was interpreted by 3 centers, 9300 reports were obtained, including 905 (9.7%) that were inadequate and 2632 (28.3%) that were positive. The percentage of cases in which all 3 reports were inadequate increased with increasing age of the women and with inadequate cytology. The highest percentage of adequacy in all 3 reports and of cases with all 3 reports positive was observed in specimens from women who had grade ≥2 cervical intraepithelial neoplasia (CIN2+), atypical squamous cells of undetermined significance or more severe (ASC-US+) cytology, or mRNA positivity. The number of inadequate reports was significantly associated with increasing age, inadequate cytology, mRNA negativity, and scant cellularity. A positive p16/Ki-67 report was associated with an ASC-US+ result and with a positive mRNA result in cases both with and without CIN2+ but was associated with an HPV type 16 and/or 18 infection only in CIN2+ cases. The presence of CIN2+ was strongly associated with dual staining positivity.

CONCLUSIONS

The interpretation of p16/Ki-67 results may be influenced by several different variables, all of which are part of the steps in the procedure, and by the characteristics of the screened population.

Implementation of p16/Ki67 dual stain cytology in a Danish routine screening laboratory: Importance of adequate training and experience

Background

Immunocytochemical staining with p16/Ki67 has been suggested as a promising triage biomarker in cervical cancer screening. As dual staining is a subjective method, proper training may be required to ensure safe implementation in routine laboratories and reduce risk of misclassification. We determined concordance between novice evaluators and an expert, stratified by number of slides reviewed at three reading points.

Methods

The study was conducted at the Department of Pathology, Randers, Denmark. Women were eligible if they were aged ≥45, had been enrolled in one of two ongoing clinical studies, and had a dual stain slide available. Dual staining was performed using the CINtec plus assay. Slides were randomly selected from three reading points at which novice evaluators had reviewed <30, ~300, and ≥500 dual stain slides respectively. Level of concordance was estimated using Cohen's Kappa, κ.

Results

Of 600 eligible slides, 50 slides were selected for review as recommended by the manufacturer. Median age was 68 years (range: 58‐74). Overall concordance was good (κ = 0.68, 95% confidence interval [CI]: 0.60‐0.76), with an overall agreement of 84% (95% CI: 70.9%‐92.8%). Concordance improved with increasing number of slides reviewed at a given reading point, from a moderate concordance (κ = 0.47, 95% CI: 0.05‐0.90) after reviewing <30 slides to a good concordance (κ = 0.66, 95% CI: 0.20‐0.88) and a very good concordance (κ = 0.88, 95% CI: 0.66‐1.00) after reviewing ~300 and ≥500 slides, respectively.

Conclusions

When interpreting dual stain slides from older women, concordance increased slightly as novice evaluators received more training and experience. Although further evaluation is warranted, these findings indicate that a significant amount of training and experience of novice evaluators may be needed to ensure accurate dual stain interpretation in this age group. Future studies should accurately describe training and experience of evaluators to enable a better comparison of concordance and diagnostic accuracy across studies.

Trial registration

NCT04114968 and NCT04298957.

Evaluation of the training program for p16/ Ki-67 dual immunocytochemical staining interpretation for laboratory staff without experience in cervical cytology and immunocytochemistry

Background

p16/Ki-67 dual immunocytochemical staining (DS) is considered easy to interpret if evaluators are properly trained, however, there is no consensus on what constitutes proper training. In the present study we evaluated a protocol for teaching DS evaluation on students inexperienced in cervical cytology.

Methods

Initial training on 40 DS conventional smears was provided by a senior cytotechnologist experienced in such evaluation. Afterwards, two students evaluated 118 cases. Additional training consisted mainly of discussing discrepant cases from the first evaluation and was followed by evaluation of new 383 cases. Agreement and accuracy of students’ results were compared among the participants and to the results of the reference after both evaluations. We also noted time needed for evaluation of one slide as well as intra-observer variability of the teacher’s results.

Results

At the end of the study, agreement between students and reference was higher compared to those after initial training (overall percent agreement [OPA] 81.4% for each student, kappa 0.512 and 0.527 vs. OPA 78.3% and 87.2%, kappa 0.556 and 0.713, respectively). However, accuracy results differed between the two students. After initial training sensitivity was 4.3% points and 2.9% points higher, respectively compared to the reference, while specificity was 30.6% points and 24.4% points lower, respectively, compared to the reference. At the end of the study, the sensitivity reached by one student was the same as that of the reference, while it was 2.6% points lower for the other student. There was a statistically significant difference in specificity between one student and the reference and also between students (16.7 and 15.1% points). Towards the end of the study, one student needed 5.2 min for evaluating one slide while the other needed 8.2 min. The intra-observer variability of the senior cytotechnologist was in the range of “very good” in both arms of the study.

Conclusions

In teaching DS evaluation, the students’ progress has to be monitored using several criteria like agreement, accuracy and time needed for evaluating one slide. The monitoring process has to continue for a while after students reach satisfactory results in order to assure a continuous good performance. Monitoring of teacher’s performance is also advisable.

Interlaboratory concordance of p16/Ki-67 dual-staining interpretation in HPV-positive women in a screening population

BACKGROUND

p16/Ki-67 dual staining is a candidate biomarker for triaging human papillomavirus (HPV)-positive women. Reproducibility is needed for adopting a test for screening. This study assessed interlaboratory reproducibility in HPV-positive women.

METHODS

All women positive for HPV from the Italian New Technologies for Cervical Cancer 2 study, were included in this study. ThinPrep slides were immunostained for p16/Ki-67 in 4 laboratories and were interpreted in 7 laboratories. Each slide had 3 reports from different laboratories. Slides were classified as valuable or inadequate, and valuable slides were classified as positive (at least 1 double-stained cell) or negative. Interlaboratory reproducibility was evaluated with κ values.

RESULTS

Overall, we obtained 9300 reports for 3100 cases; 905 reports (9.7%) were inadequate. The overall adequacy concordance was poor (κ = 0.224; 95% confidence interval [CI], 0.183-0.263). The overall positivity concordance was moderate (κ = 0.583; 95% CI, 0.556-0.610). Of the 176 cervical intraepithelial neoplasia 2+ (CIN-2+) lesions found in HPV DNA-positive women, 158 had a valid result: 107 were positive in all 3 reports (sensitivity for CIN-2+, 67.7%; 95% CI, 59.8%-74.9%), 23 were positive in 2 reports (sensitivity of the majority report, 82.3%; 95% CI, 75.4%-87.9%), and 15 were positive in 1 report (sensitivity of at least 1 positive result, 91.8%; 95% CI, 86.3%-95.5%). Thirteen CIN-2+ cases were negative in all 3 reports. The overall positivity concordance in CIN-2+ samples was κ = 0.487 (95% CI, 0.429-0.534), whereas in the non-CIN-2+ samples, it was κ = 0.558 (95% CI, 0.528-0.588).

CONCLUSIONS

The p16/Ki-67 assay showed poor reproducibility for adequacy and good reproducibility for positivity comparable to that of cervical cytology. Nevertheless, the low reproducibility does not affect the sensitivity for CIN-2+.

Interobserver variability and accuracy of p16/Ki-67 dual immunocytochemical staining on conventional cervical smears

Background

p16/Ki-67 dual immunocytochemical staining (DS) has been proven as a sensitive and specific test for triage of HPV positive women with good reproducibility and accuracy. However, implementation of the test into an organized screening program (OSP) is not easy. The aims of this study were to compare the performance and agreement of DS results among three Slovenian cytopathological laboratories involved in the national OSP, and to define cases where staining results can be difficult to interpret.

Methods

Cervical smears were obtained for DS from 129 women referred to colposcopy. Smears were evaluated blindly in three laboratories by a cytotechnologist and a cytopathologist after initial training. Results were positive, suspicious, negative or inadequate. Five characteristics of DS staining were recorded. After primary evaluation, an extensive expert-led additional training was undertaken, including a discussion of difficult cases and a practical exam. Smears were re-evaluated and results compared to primary evaluation.

Results

After the additional training, the overall percentage of agreement among the three laboratories increased from 77.5 to 89.9% and kappa increased from 0.70 to 0.86. Sensitivity for CIN2+ increased in two laboratories, to 90.5 and 85.7%, without the loss of specificity (75.8%). In one laboratory, the sensitivity slightly decreased from 90.5 to 88.9%, but the specificity increased from 63.6 to 68.2%. Difficult cases had significantly less DS cells, weak intensity of p16 staining, suboptimal cell morphology and background staining compared to positive cases.

Conclusion

Additional expert-led training and discussion of difficult cases are necessary for accurate interpretation of DS in laboratories involved in OSP. The most difficult cases were those with single stained cells and weak p16 staining. Training protocol for safe implementation of p16/Ki-67 DS in OSP is proposed.

Electronic supplementary material

The online version of this article (10.1186/s13000-019-0821-5) contains supplementary material, which is available to authorized users.

Clinical Utility of CINtec PLUS Triage in Equivocal Cervical Cytology and Human Papillomavirus Primary Screening

OBJECTIVES

While cervical cytology is accepted triage for human papillomavirus (HPV)-positive women, the efficiency of cervical screening could be improved by exploiting disease markers with higher specificity.

METHODS

CINtec PLUS triage alone and combined with HPV 16/18 genotyping was performed on ThinPrep samples from HPV-positive women. Clinical performance and the potential to reduce or expedite colposcopy referrals were evaluated.

RESULTS

The 2-year sensitivity and specificity for cervical intraepithelial neoplasia grade 3 or worse (CIN3+) were 90% and 42%, respectively. Specificity was improved over HPV testing in equivocal cytology and could cut the referral rate by about 40%. When combined with HPV 16/18 genotyping, CINtec PLUS triage of the 12 other high-risk HPV genotypes generally demonstrated better sensitivity for CIN3+ than separate triage of non-type-specific HPV-positive women. This strategy could reduce colposcopy referrals by 31%.

CONCLUSIONS

These findings highlight the potential of CINtec PLUS to improve management pathways in HPV-positive women. CINtec PLUS cytology represents a sensitive and efficient triage in HPV-positive women. The clinical performance of the dual-stain was most notable in women younger than 25 years and could potentially improve management pathways.