Background To the authors’ knowledge, published studies reporting on the performance of the FocalPoint GS (FPGS) imaging system have yielded conflicting results to date. However, the results of the MAVARIC study indicated that the FPGS “No Further Review” (NFR) aspect of the technology demonstrated potential and warranted further investigation. The current validation study was performed prior to implementing the NFR slide reporting technology within the routine cervical screening program in Wales, United Kingdom. Methods A total of 45,317 SurePath liquid‐based cytology cervical screening samples were submitted for FPGS scanning by 4 Welsh laboratories between 2006 and 2011. The current study (Computer Assisted Evaluation, Screening and Reporting [CAESAR]), reports on a comparison between slides categorized as NFR (8130 slides) and slides manually screened as negative (93,473 slides). Both interventions had a subsequent negative quality control screen. Results The histological outcome rates of cervical intraepithelial neoplasia 2 (CIN‐2) (high‐grade squamous intraepithelial lesion or worse [HSIL+]) at 2 years and subsequently 3 years after an FPGS NFR result versus a manually screened negative result were compared. Significantly fewer cases were detected in the NFR cohort compared with the manually screened cohort (P = .043 at 2 years and P = .027 at 3 years). When these cases were subcategorized as cancers and precancers, the interval cancer prevalence between NFR and manually screened samples at 2 years and 3 years was similar; however, the interval precancer prevalence for FPGS NFR was significantly lower (P = .023 at 2 years and P = .026 at 3 years) at approximately one‐half that of manual screening. Conclusions The negative predictive potential of the FPGS NFR technology is higher than that of manual screening, and the technology has quality/throughput benefits to support and enhance a laboratory cervical screening service.
BACKGROUND The MAVARIC study supported the use of the FocalPoint GS (FPGS) imaging system “No Further Review” (NFR) technology for cervical screening and recommended further investigation. A validation study (Nuttall et al.) was performed by Cervical Screening Wales before implementing the NFR slide reporting technology within the cervical screening program in Wales, United Kingdom. METHOD A total of 45,317 SurePath liquid‐based cytology cervical screening samples were submitted for FPGS scanning within four Welsh cytology laboratories between 2006 and 2011. The study, Computer Assisted Evaluation, Screening and Reporting, involved scanning the slides using the FPGS and comparing the results with manual screening performed under established Cervical Screening Wales protocols. RESULTS An increased number of abnormal cases presented in the NFR reporting category, significantly greater than that previously encountered. This anomaly resulted in higher false‐negative rates with potentially life‐changing consequences for the screening participant. Subsequent investigation determined that this increase in cases created an algorithm cascade or “sump” effect, which resulted in an unprecedented increased number of samples categorized as NFR. This exceeded the calibration parameters set for the FPGS and was thought to be caused by an increase in the number of younger women attending for screening following the death of a young reality television celebrity from cervical cancer. CONCLUSION Adequate and timely calibration of FPGS technology is vital for quality assurance of the results produced, particularly following events that may impact on cervical precancer incidence rates. Failure to do so can result in potentially catastrophic screening incidents that are avoidable.
Currently, UK cervical screening programmes operate a 3000 minimum slide threshold for cytology screening staff. Post implementation of primary human papillomavirus (pHPV) testing, cytology screening will decrease substantially—by 85%–90%, depending on the HPV positivity rate. This report outlines revised minimum workload proposals that are arguably better suited to modern laboratory cervical screening services.
The use of computer assisted screening (CAS) in cervical screening is established in the USA and Europe and is currently undergoing trials in the UK (HTA). Following the introduction of SurePath™ LBC technology to Wales, Cervical Screening Wales (CSW) has implemented a study into applications of CAS within the CSP in Wales, agreed during LBC procurement negotiations. Technological support was provided by TriPath Europe and Medical Solutions UK Ltd. Evaluation centred on the use of CAS in Quality Assurance procedures, comparing it with rapid screening (review and preview), as HTA studies are already established to assess the primary screening role. Assessment included • Evaluation of CAS across a laboratory network – assessing sample identification, tracking processes and transportation • Assessment of Quintile Ranking verses abnormality distribution • Assessment of the NFR (no further review) category as a reliable indicator of sample negativity • Monitoring screener performance using CAS: Focal Point/LGS has the capability to monitor operator/observer functions Three laboratories in North Wales participated in the study. Slides were scanned centrally using Focal Point LGS and returned to laboratories for assessment. Slide assessment followed a twin track protocol. • The ‘manual’ arm assessed slides according to standard laboratory procedures • The ‘CAS’ arm assessed slides using location guidance and screening Data were collected and analysed by CSW. Approximately 12 000 samples were scanned; results were compared for both arms. Results show that the technology has a number of benefits, in supporting and enhancing performance within the screening programme. • CAS compares favourably with rapid screening • Quintile ranking data reflects the distribution of abnormalities • The technology is well suited to shared use through laboratory networks • Variations in screener aptitude were noted.
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