Results of the implementation of liquid-based cytology-SurePath in the Ontario screening program

Validation of a New Low-Cost, Methanol-Based Fixative for Cervical Cytology and Human Papillomavirus Detection

OBJECTIVE

To test the performance of a new fixative for pap smear collection for liquid-based cervical cytology, CellPreserv® and compare it with the commercially available, PreservCyt® used in the diagnosis and detection of human papillomavirus (HPV).

METHODS

Seven hundred twenty five women participated in this study after signing an informed consent. The specimens were collected using a traditional device, agitated in PBS, and equally divided in both fixatives. The slides were prepared routinely, stained by Papanicolaou, examined blindly by 2 cytologists, and reviewed by one cytopathologist. To search for HPV, 1,000 μL from each fixative was taken and processed by polymerase chain reaction.

RESULTS

Considering the adequacy of samples, both fixatives had similar results - 0.33 and 0.32% of the cases unsatisfactory for PreservCyt® and CellPreserv®, respectively. Considering the 701 satisfactory cases and comparing the new fixative to the traditional fixative, there was 99.3% concordance between both. The results regarding the HPV detection was 100% concordant between the 2 fixatives.

CONCLUSION

The new methanol-based fixative, CellPreserv®, is cheaper and equally efficient for treating cervical cancer screening and for HPV detection, and can be safely used by the health system prevailing in low-income countries.

Cervical cancer incidence after normal cytological sample in routine screening using SurePath, ThinPrep, and conventional cytology: population based study

Objective To compare the cumulative incidence of cervical cancer diagnosed within 72 months after a normal screening sample between conventional cytology and liquid based cytology tests SurePath and ThinPrep.Design Retrospective population based cohort study.Setting Nationwide network and registry of histo- and cytopathology in the Netherlands (PALGA), January 2000 to March 2013.Population Women with 5 924 474 normal screening samples (23 833 123 person years).Exposure Use of SurePath or ThinPrep versus conventional cytology as screening test.Main outcome measure 72 month cumulative incidence of invasive cervical cancer after a normal screening sample for each screening test. Cox regression analyses assessed the hazard ratios, adjusted for calendar time, age, screening history, and socioeconomic status and including laboratories as random effects.Results The 72 month cumulative cancer incidence was 58.5 (95% confidence interval 54.6 to 62.7) per 100 000 normal conventional cytology samples, compared with 66.8 (56.7 to 78.7) for ThinPrep and 44.6 (37.8 to 52.6) for SurePath. Compared with conventional cytology, the hazard of invasive cancer was 19% lower (hazard ratio 0.81, 95% confidence interval 0.66 to 0.99) for SurePath, mainly caused by a 27% lower hazard (0.73, 0.57 to 0.93) of a clinically detected cancer. For ThinPrep, the hazard was on average 15% higher (hazard ratio 1.15, 0.95 to 1.38), mainly caused by a 56% higher hazard of a screen detected cancer (1.56, 1.17 to 2.08).Conclusions These findings should provoke reconsideration of the assumed similarity in sensitivity to detect progressive cervical intraepithelial neoplasia between different types of liquid based cytology and conventional cytology.

Comparing SurePath, ThinPrep, and conventional cytology as primary test method: SurePath is associated with increased CIN II+ detection rates

Purpose

Within the last decade, SurePath and ThinPrep [both liquid-based cytology (LBC) tests] have replaced conventional cytology (CC) as primary test method in cervical cancer screening programs of multiple countries. The aim of our study was to examine the effect in the Dutch screening program.

Methods

All primary smears taken within this program from 2000 to 2011 were analyzed using the nationwide registry of histo- and cytopathology (PALGA) with a follow-up until March 2013. The percentage of smears classified as borderline/mildly dyskaryotic (BMD) and >BMD as well as CIN and cervical cancer detection rates were compared between SurePath and ThinPrep versus CC by logistic regression analyses (adjusted for age, screen region, socioeconomic status, and calendar time).

Results

We included 3,118,685 CC, 1,313,731 SurePath, and 1,584,587 ThinPrep smears. Using SurePath resulted in an increased rate of primary smears classified as >BMD [odds ratio (OR) = 1.12 (95% confidence interval (CI) 1.09–1.16)]. CIN I and II⁺ detection rates increased by 14 % [OR = 1.14 (95% CI 1.08–1.20)] and 8 % [OR = 1.08 (95% CI 1.05–1.12)]. Cervical cancer detection rates were unaffected. Implementing ThinPrep did not result in major alterations of the cytological classification of smears, and it did not affect CIN detection rates. While not significant, cervical cancer detection rates were lower [OR = 0.87 (95% CI 0.75–1.01)].

Conclusions

The impact of replacing CC by LBC as primary test method depends on the type of LBC test used. Only the use of SurePath was associated with increased CIN II⁺ detection, although it simultaneously increased the detection of CIN I.

HPV testing is an efficient management choice for women with inadequate liquid-based cytology in cervical cancer screening

This study compares colposcopy referrals of 2 management strategies: oncogenic human papillomavirus (HPV)-DNA testing (Hybrid Capture 2 assay, Qiagen, Germantown, MD) and repeat cytology. In the New Technology in Cervical Cancer Trial, 22,708 subjects were randomly assigned to undergo both HPV and liquid-based cytologic testing. Women aged 35 to 60 years old with unsatisfactory cytologic findings were directly referred for colposcopy if the HPV test result was positive, and were referred for repeat cytologic examination if the HPV test result was negative; women aged 25 to 35 years old were referred for repeat cytologic examination independent of HPV test results. A positive or a second unsatisfactory cytologic examination referred women for colposcopy. Five hundred sixty women had unsatisfactory cytologic findings. Colposcopy referral was not significant and slightly higher with HPV testing than repeat cytologic test (9.8% vs 6.8%, P = .11). When cytologic testing was repeated 36.8% were unavailable for follow-up and most of the colposcopies were performed in HPV-negative women. For unsatisfactory cytologic findings, HPV triage is a more logical and efficient management strategy than a repeat cytologic test.

Unsatisfactory rates vary between cervical cytology samples prepared using ThinPrep and SurePath platforms: a review and meta-analysis

OBJECTIVE

To compare unsatisfactory rates between the two major liquid-based cytology (LBC) platforms, namely ThinPrep (Hologic) and SurePath (Becton Dickinson).

DESIGN

The authors performed both a systematic review and a meta-analysis. Inclusion criteria were English language, data presented on unsatisfactory rates for either ThinPrep or SurePath, utilising actual patient samples (ie, not laboratory manipulated samples) and no manipulation using acetic acid to increase the satisfactory rate. The authors searched PubMed for articles using the keywords 'SurePath' or 'ThinPrep' and 'unsatisfactory'. References of retrieved studies were searched for additional articles. Key researchers in the field were also contacted.

PARTICIPANTS AND INTERVENTIONS

Eligible studies were reviewed for rates of unsatisfactory cervical cytology smears processed on either the ThinPrep or SurePath platforms (compared with a general linear model) or data on unsatisfactory rates for both platforms for the same laboratory and the same patient population (compared with a meta-analysis using a random effects model and pooled RR).

PRIMARY OUTCOME MEASURE

Unsatisfactory rate of cervical cytology smears.

RESULTS

A total of 1 120 418 cervical cytology smears were reported in 14 different studies using the SurePath platform for an overall unsatisfactory rate (weighted average) of 0.3%. 28 studies reported on 1 148 755 smears prepared using the ThinPrep platform for an overall unsatisfactory rate (weighted average) of 1.3%. The general linear model did not show a difference between LBC platforms when other variables were controlled for; however, the power to detect a difference (0.087) was very low. The meta-analysis performed on four studies where both ThinPrep and SurePath results were reported from the same laboratory showed fewer unsatisfactory tests from the SurePath platform (RR 0.44, 95% CI 0.25 to 0.77, p=0.004).

CONCLUSIONS

Multiple factors affect LBC unsatisfactory rates. In a meta-analysis, cervical cytology samples prepared on the SurePath platform show significantly fewer unsatisfactory smears than those prepared on the ThinPrep platform.

Unsatisfactory SurePath liquid-based Papanicolaou tests: causes and significance

BACKGROUND

The introduction of liquid-based Papanicolaou (Pap) tests (LBPTs) has reduced the incidence of unsatisfactory Pap tests (UPTs), but little is known about their causes and significance, especially in the case of SurePath LBPTs.

METHODS

All unsatisfactory LBPTs from January 1, 2003 to December 31, 2006 were retrieved. The characteristics of patients, providers, and LBPTs; the reason for UPTs; and any cytologic or histologic follow-up within 24 months were recorded. Negative Pap tests that were evaluated immediately after a UPT served as a control group.

RESULTS

Of 243,006 Pap tests (95.5% SurePath LBPTs), 0.23% were unsatisfactory. Scant cellularity was the primary cause of SurePath UPT. Women in this UPT group were older, had more diagnostic Pap tests taken, less frequently were taking contraceptives or were pregnant, and were more likely to be menopausal or posthysterectomy. The 278 women who had UPTs had significantly higher rates of follow-up Pap tests (65.1% vs 22.2%), abnormal Pap tests (5.4% vs 1.4%), biopsies (10% vs 1%), and abnormal biopsies (5% vs 1%) than the 284 women in the control group, including 7 women with cervical intraepithelial neoplasia 1 (CIN-1), 1 woman with CIN-2, 4 women with CIN-3, and 2 women with endometrial hyperplasia. The UPT rates varied little between provider groups (physicians vs nonphysicians and gynecologists vs nongynecologists).

CONCLUSIONS

The frequency of UPTs in a predominantly SurePath LBPT-screened population was very low and was caused mainly by low cellularity. Similar to conventional Pap smears, unsatisfactory SurePath LBPTs had a higher risk of significant histologic abnormalities on follow-up than negative satisfactory Pap tests and could have benefited from a repeat Pap test or other evaluation, according to current management guidelines.

Superior performance of liquid-based versus conventional cytology in a population-based cervical cancer screening program

OBJECTIVE

Liquid-based cytology may offer improvements over conventional cytology for cervical cancer screening. The two cytology techniques were compared in a group of 86,469 women who participated in a population-based screening program. Using a nation-wide pathology database containing both cervical cytology and histology records for all patients, we compared the outcome of the two screenings methods with regard to the detection rate of histological proven abnormalities and the determination of the true false-negative rates for both methods.

METHODS

Two cohorts of women living in the same geographical region were used. Cohort 1 (n=51,154 women) was analysed using conventional cytology (conventional cohort) and cohort 2 (liquid cohort) (n=35,315 women) was analysed using liquid-based cytology (SurePath). The samples were processed in one laboratory. The results of histological follow up were available via a central database.

RESULTS

The rate of unsatisfactory slides was significantly lower using liquid-based cytology (0.13% vs. 0.89%, p<0.0001). Detection of ASCUS+ (Atypical squamous cells of unknown significance or higher abnormalities) was significantly higher using liquid-based cytology (2.97% vs. 1.64%, p<0.0001), mainly due to the increase in the ASCUS category. The percentage of histological abnormalities within the ASCUS samples was approximately equal in both cohorts, indicating that more true abnormal cases were detected using liquid-based cytology. The sensitivity for detection of a histological proven lesion is significantly higher in the liquid cohort compared to the conventional cohort (96.2% vs. 92.0%), with only a slight difference in specificity (97.8% vs. 98.2%).

CONCLUSION

This population study confirmed previous institution-based reports of decreased numbers of unsatisfactory samples based on liquid-based cytology and showed an increased sensitivity for the detection of cytological abnormalities that was validated by subsequent histological investigation.

A randomised comparison of SurePath liquid-based cytology and conventional smear cytology in a colposcopy clinic setting

OBJECTIVE

The objective of this study was to compare the sensitivity of cervical cytology using conventional smears and SurePath liquid-based cytology (LBC).

DESIGN

Prospective randomised evaluation of diagnostic test.

SETTING

A single institution colposcopy clinic.

POPULATION

Women attending first visit colposcopy appointments were offered entry into the study.

METHODS

Cervical cytology samples from 913 women of age 16-75 years were randomly processed as SurePath LBC or conventional smears. Conventional smears were taken for 453 women and a SurePath LBC taken for 451 women. Cytology results were correlated with colposcopic findings and histology from colposcopic biopsies, treatment and follow up.

MAIN OUTCOME MEASURES

To compare the sensitivity of SurePath LBC and conventional smears for histologically proven abnormality. Other outcome measures include a comparison of their sensitivity for high-grade abnormalities and their satisfactory rate.

RESULTS

Accounting for all randomised samples, there was a trend towards improved sensitivity for SurePath LBC (79.1 versus 73.7%, P = 0.1). However, excluding unsatisfactory cytology (and samples not taken) eliminated this trend; the sensitivity for both LBC and conventional smears for any epithelial abnormality was 81%. With a threshold of atypical squamous cells of uncertain significance (ASC-US), both SurePath LBC and conventional smears had a sensitivity of 92% for high-grade lesions. SurePath LBC was less likely to be reported as unsatisfactory (2.7 versus 9.1%, P < 0.0001).

CONCLUSIONS

In this context, with a threshold of ASC-US, both SurePath LBC and conventional smears offer high sensitivity for the detection of CIN2/3, but SurePath LBC is less likely to be reported as unsatisfactory.

Liquid-based cytology versus conventional Papanicolaou smear in an organized screening program : a prospective randomized study

BACKGROUND

The objective of this study was to evaluate whether liquid-based cytology (LBC) can improve high-standard cervical cancer screening cytology further. The primary endpoint was histopathologic high-grade lesions in current and subsequent screening rounds. The secondary endpoints were cytologic diagnosis and inadequate samples.

METHODS

Women were randomized to smear taking by conventional Papanicolaou (Pap) smear or LBC according to the time of appointment. Eight thousand eight hundred ten conventional Pap smears and 4674 LBC samples were included. Evaluations of atypical cytology and referral to colposcopy and treatment were performed as routine procedures. Histopathologic diagnoses were retrieved from a regional database 8 months after the study was closed. The mean follow-up was 2 years and 9 months.

RESULTS

Inadequate samples were observed in 0.3% of LBC samples versus 0.7% of Pap smears (P = .002). The total fraction of nonbenign diagnoses in cytology was 4.5% versus 3.5%, respectively (P < .001). Histopathologic evaluation was made on 570 patients constituting 4.6% of the LBC samples and 4% of the Pap smears. Forty percent more high-grade lesions were identified as a result of LBC sampling (1.20% vs 0.85%; P = .05). The influence of the sampling method was significant for all variables (odds ratio [OR], 1.60; 95% confidence interval [95% CI], 1.12-2.28) for high-grade lesions that were identified by histology when adjusting for age and screening unit in a logistic regression model. At the second follow-up 2 years and 1 month later, the OR was decreased only slightly (1.51; 95% CI, 1.13-2.01).

CONCLUSIONS

In the ongoing cervical screening program of western Sweden, liquid cytology produced a significantly higher yield of histologic high-grade lesions compared with conventional Pap smears.

Evolution of Pap testing at a community hospital: a ten year experience

Over a 10-year period the Pap program at our community hospital laboratory progressed from the use of 100% conventional smears to predominantly ThinPrep (TP) and then to nearly 100% SurePath (SP). During this period the annual Pap volume grew from less than 20,000 to nearly 50,000. This retrospective review focuses on improvements in high-grade squamous intraepithelial lesion (HSIL) detection rates and specimen adequacy rates during the 10-year period. The laboratory database was used to identify 310,080 Pap test records between 1995 and 2004 inclusive. Pap type differences in HSIL detection rates and specimen adequacy rates were examined using the Cochran-Mantel-Haenszel test, with year as the stratification variable. The Breslow-Day test was used to evaluate the consistency of differences across the years. The overall results are summarized below in tabular format. Results of Combined 10-Year Data for Total Number of Cases, HSIL Rate, and Unsatisfactory Specimen Rate by Pap Method are given: [table: see text]. HSIL detection rates were significantly higher for liquid-based Pap tests compared with conventional smears (P < 0.0001). In addition, SP was associated with higher HSIL detection rates than TP with an estimated common odds ratio (OR) of 1.37 (95% confidence interval (CI), 1.10 - 1.71; P = 0.005), and higher specimen adequacy compared with TP or conventional Pap methods (P < 0.0001).

Liquid-based cytology for cervical cancer screening

In multiple studies during the last decade, liquid-based cytology for cervical cancer screening has been shown to increase the detection rate for preneoplastic squamous intraepithelial lesions equal to or greater than the conventional Papanicolaou (Pap) smear method. Liquid-based collection and processing provide more representative cervical sampling than conventional smearing of the specimen on a glass slide. Currently, there are two test methodologies that are widely marketed and available to clinical laboratories, health systems and clinicians that undertake cervical cytology. The purpose of this article is to provide an overview of the methodology and performance of SurePath Liquid-Based Pap Test in cervical cytology screening. The SurePath liquid-based Pap test significantly reduces the unsatisfactory rate of Pap test slides, and detects a significantly higher number of low- and high-grade squamous lesions when compared with the conventional Pap smear technique. Biopsy confirmation shows that this increased detection does not come at a cost of decreasing specificity, and sensitivity for histologic dysplasia is equal to or greater than the best available data for the conventional Pap method. The SurePath collection vial provides residual cellular material for adjunctive out-of-the-vial molecular testing, including sexually transmitted diseases and oncologic biomarkers associated with cervical carcinoma. Finally, SurePath slides can be placed on an automated cervical cytology screening device (FocalPoint), thus providing improved disease detection and enhanced laboratory productivity.

Dutch solutions for liquid-based cytology: analysis of unsatisfactory slides and HPV testing of equivocal cytology

The liquid-based techniques to obtain microscopy slides for cervical screening have replaced conventional smears almost completely in the USA, but not in all European countries. The decision making process to use liquid-based cytology (LBC) for nationwide screening programs depends on the health system. In a pilot study of over 7,000 screenees, we analyzed the unsatisfactory LBC slides and tested the equivocal cytologies for HPV by using the LiPA test. For comparison over 48,000 conventional screening data were used. Compared to conventional smears, the LBC slides were highly cellular, the state of fixation was much better, and obscuring blood did not exist. The unsatisfactory rate showed an increase from 262/100,000 (conventional smears) to 357/100,000 (LBC slides) due to too thick, undiagnosable epithelial fragments on the LBC slides. HPV testing of the equivocal cytology leads to a better patient management and less unnecessary referrals.

Human Papillomavirus Testing and Liquid-Based Cytology: Results at Recruitment From the New Technologies for Cervical Cancer Randomized Controlled Trial

BACKGROUND

Although testing for human papillomavirus (HPV) has higher sensitivity and lower specificity than cytology alone for detecting cervical intraepithelial neoplasia (CIN), studies comparing conventional and liquid-based cytology have had conflicting results.

METHODS

In the first phase of a two-phase multicenter randomized controlled trial, women aged 35-60 years in the conventional arm (n = 16,658) were screened using conventional cytology, and women in the experimental arm (n = 16,706) had liquid-based cytology and were tested for high-risk HPV types using the Hybrid Capture 2 assay. Women in the conventional arm were referred to colposcopy with atypical cells of undetermined significance (ASCUS) or higher and those in the experimental arm were referred with ASCUS or higher cytology or with a positive (> or = 1 pg/mL) HPV test. Sensitivity and positive predictive value (PPV) for detection of cervical intraepithelial neoplasia grade 2 or higher (CIN2+) were calculated.

RESULTS

The screening methods and referral criterion applied in the experimental arm had higher sensitivity than that in the conventional arm (relative sensitivity = 1.47; 95% confidence interval [CI] = 1.03 to 2.09) but a lower PPV (relative PPV = 0.40; 95% CI = 0.23 to 0.66). With HPV testing alone at > or = 1 pg/mL and at > or = 2 pg/mL, the gain in sensitivity compared with the conventional arm remained similar (relative sensitivity = 1.43, 95% CI = 1.00 to 2.04 and relative sensitivity = 1.41, 95% CI = 0.98 to 2.01, respectively) but PPV progressively improved (relative PPV = 0.58, 95% CI = 0.33 to 0.98 and relative PPV = 0.75, 95% CI = 0.45 and 1.27, respectively). Referral based on liquid-based cytology alone did not increase sensitivity compared with conventional cytology (relative sensitivity = 1.06; 95% CI = 0.72 to 1.55) but reduced PPV (relative PPV = 0.57; 95% CI = 0.39 to 0.82).

CONCLUSIONS

HPV testing alone was more sensitive than conventional cytology among women 35-60 years old. Adding liquid-based cytology improved sensitivity only marginally but increased false-positives. HPV testing using Hybrid Capture 2 with a 2 pg/mL cutoff may be more appropriate than a 1 pg/mL cutoff for primary cervical cancer screening.