1. LBC – Sink or Swim? Thames Valley Cytology Society Bedford 24th June 2004

2. 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

3. 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.

6. 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%

7. 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

8. The Problem The Problem The Conventional Cervical Smear Non-randomized
A cervical sample
containing precancerous
cells (red)
Non-randomized
portion of cells
Over 80% of
cells discarded
Sample may not
reflect patient’s
actual condition
Smear spray-fixed
and sent to lab
Missing cells,
obscuring elements

9. 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

10. Evidence Base Clinical Validation ThinPrep® Improvement
Patients LSIL+ HSIL+ S.Q.
Split-Sample Lee et al. 6, % 36% 54%
Corkill et al. 1, % 54% N/A
Roberts et al. 81, % 15% 91%
Direct-to-Vial Scottish Pilot 30,228 92% 84% 76%
Diaz-Rosario 56,339 72% 103% ???
Papillo et al. 8, % 55% 52%
Weintraub et al. 18, % 94% 93%
Bolick 10, % 173% 70%
Johnson et al % 125% 41%
Guidos/Selvaggi 9, % 233% 97%
Quddus 14, % 35% 28%
Hornish 30, N/A 83% N/A
>60 peer reviewed international publications from 4 Continents

11. 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

12. Does LBC decrease inadequate rates?
SurePath cells
Thinprep cells
Conventional cells?

13. Scottish Pilot Results
Weighted Average (total 30,228)
Conventional % ThinPrep %
Unsatisfactory
Borderline
Mild %↑
Moderate
Severe % ↑

14. 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

15. HPV Triage Negative Borderline Mild dyskaryosis Moderate/severe
Cancer
COLPOSCOPY/
BIOPSY
HPV Testing
NO TREATMENT

16. 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

17. ThinPrep® T2000 Processor

18. ThinPrep® 3000 Processor

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

20. SurePath SurePath and ThinPrep Similarities: Diagnostic rates
Detection rates of HPV from vial
Histology/Cytology correlation rates

21. SurePath SurePath and ThinPrep Differences: Inadequate rates
False negative fraction
Detection of abnormalities in clusters

22. SurePath SurePath and ThinPrep Inadequate rates:

23. SurePath SurePath and ThinPrep False negative fraction: LSIL % HSIL %
SurePath screened TWICE ; ThinPrep screened ONCE

24. SurePath SurePath and ThinPrep Abnormalities in clusters:
AGUS Endom Adenoca
SurePath
ThinPrep

25. LBC 5 year conversion timescale is too long LBC is on the way.
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