LBC

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LBC Sink or Swim?Thames Valley Cytology
SocietyBedford24th June 2004
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NICE Guidance

• October 2003
• NICE recommends that LBC is used as
• the primary means of processing samples
• in the cervical screening programme in
• England and Wales

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NICE Guidance

• There is currently insufficient evidence to
• recommend one LBC product over
• another.
• The NHSCSP and SCW may wish to
• consider evaluating further different
• products as the method is introduced.

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Conventional Smears

• False Negative Rate of up to 55
• Sampling and interpretative errors
• Borderline Rates of up to 6.4
• 70 are truly negative
• 30 represent more severe abnormality
• Inadequate Rates of 9.7

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Sources Of False Negatives

• Sampling issues (70)
• cells not collected on the sampling device
• cells collected, but not transferred to the slide
• Interpretative issues (30)
• abnormal cells present on slide but either not
  seen or misinterpreted

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The Problem
The Problem
The Conventional Cervical Smear
Non-randomized portion of cells
A cervical sample containing precancerous cells
(red)
Over 80 of cells discarded
Sample may not reflect patients actual
condition
Smear spray-fixed and sent to lab
Missing cells, obscuring elements
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The Solution
The Solution
The ThinPrep Pap Test
Virtually 100 of cells collected into ThinPrep
vial
A cervical sample containing precancerous cells
(red)
Cells immediately preserved and sent to lab
Increased opportunity to detect early signs of
abnormality
Filtration process disperses, randomizes cells
More representative and clear thin layer of
cells
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Evidence Base
Clinical Validation
ThinPrep Improvement
Patients LSIL HSIL S.Q. Split-Sample Lee et
al. 6,747 65 36 54 Corkill et
al. 1,583 110 54 N/A Roberts et al. 81,754
26 15 91 Direct-to-Vial Scottish
Pilot 30,228 92 84 76 Diaz-Rosario 56,339 72
103 ??? Papillo et al. 8,574 52
55 52 Weintraub et al. 18,247 184
94 93 Bolick 10,694 181 173 70 Johnson et
al. 902 71 125 41 Guidos/Selvaggi 9,583 267
233 97 Quddus 14,216 24
35 28 Hornish 30,431 N/A 83 N/A gt60
peer reviewed international publications from 4
Continents
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Does LBC increase sensitivity?

• Educational bias
• Lab / Smear takers
• Study design bias
• Split sample / Direct-to-Vial
• Population bias
• Self-selecting / Non-screening
• End point bias
• Dyskaryosis as surrogate / lack of histological
  confirmation

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Does LBC decrease inadequate rates?

• SurePath 5000 cells
• Thinprep 40000 cells
• Conventional 50000 cells?

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Scottish Pilot Results
Weighted Average (total 30,228)
Conventional
ThinPrep Unsatisfactory 7.63
1.84 Borderline 3.98 3.67 Mild 1.10
2.12 92? Moderate 0.45
0.97 Severe 0.65 1.06 84 ?
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Scottish Pilot Conclusions

• No major storage problems
• Reduced workload for smear takers
• 349/350 smear takers preferred ThinPrep
• Increased productivity in laboratories
• Sharp reduction in the unsatisfactory rate
• Less anxiety and discomfort for women
• More appropriate referrals to colposcopy
• Allows scope for further developments
• in the screening programme

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HPV Triage

• ?Negative
• ?Borderline
• ?Mild dyskaryosis
• ?Moderate/severe
• dyskaryosis
• ?Cancer

COLPOSCOPY/ BIOPSY
HPV Testing
NO TREATMENT
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Vial storage

• Modular storage units available
• (File-a-Vial)
• 150 vial capacity

• Example
• 30,000 samples pa
• 4 week cycle
• 2,500 vials
• 17 units

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ThinPrep T2000 Processor
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ThinPrep 3000 Processor
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SurePath

• Why I like the SurePath Liquid-Based
• PAP Test
• David R Bolick
• RPS Sandy, Utah

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SurePath

• SurePath and ThinPrep
• Similarities
• Diagnostic rates
• Detection rates of HPV from vial
• Histology/Cytology correlation rates

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SurePath

• SurePath and ThinPrep
• Differences
• Inadequate rates
• False negative fraction
• Detection of abnormalities in clusters

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SurePath

• SurePath and ThinPrep
• Inadequate rates
• SurePath 0.18 26/14419
• ThinPrep 0.37 123/33198

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SurePath

• SurePath and ThinPrep
• False negative fraction
• LSIL HSIL
• SurePath 6.8 0.0
• ThinPrep 14.0 16.0
• SurePath screened TWICE ThinPrep screened ONCE

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SurePath

• SurePath and ThinPrep
• Abnormalities in clusters
• AGUS Endom Adenoca
• SurePath 0.13 0.24 0.05
• ThinPrep 0.09 0.13 0.02

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LBC

• LBC is on the way.
• 5 year conversion timescale is too long
• Major retraining exercise for labs
• Benefits in terms of productivity and scope for
  future developments
• Good for smear takers and women
• Issues around sensitivity / specificity /
  inadequate rates will be answered in long run
• Expensive solution