The ThinPrep® PapTest™

PAUL SULTANA

MLSSaturday 22 April 2023

Background

• The conventional smear has been the most successful screening test

• Screening every 3-5years has resulted in a 70% reduction in incidence

Why LBC (Liquid based cytology) has been introduced in the Malta

• Continuing improvement to the Cervical screening Programme

• Limitations of conventional cytology• Modernisation of the technique• Future benefits

– Extra tests – HPV, chlamydia, Neiseria Gonorrhoea.

Limitations Of Conventional Smear (From UK studies)

False Negative Rate of up to 55%1

Sampling and interpretive errors

Ambiguous reports of 6.4%2

70% are truly negative

30% represent more severe abnormality

Inadequate specimens of 9.7% 2

1. Hutchinson et al., AJCP, Vol 101-2; 215-219, 2. DOH Statistical Bulletin 2000/2001

Sources Of False Negatives

• Sampling issues (70%)

– cells not collected on the sampling device– cells collected, but not transferred to the slide

• Interpretive issues (30%)

– abnormal cells present on slide but either not seen or misinterpreted

How LBC is different

• Easier method for smear takers

• Technology diminishes blood, mucus & polymorphs

• Thin layer preparation

• Smaller area of the slide to screen

Conventional smear

What we see under the microscope conventional smear

The prepared slide with the new ThinPrep

What we see under the microscope. Notice the clean back ground and how well the cells are dispersed rendering easier to interpretation.

NICE recommendation is based on:

• Systematic review of literature relating to efficacy of LBC undertaken as part of the HTA programme

• New evidence from the 3 pilot sites at Bristol, Norwich and Newcastle

Summary of Results www.nice.org.uk

“Robust evidence that LBC is a cost effective alternative to conventional Pap for the health service in the UK in terms of life years saved”

Evidence of a reduction in the number of unsatisfactory specimens

Productivity of laboratories increased

Smear takers and laboratory staff liked LBC

Expect LBC will reduce the number of false negatives and the incidence of invasive cancer

ThinPrep® Pap Test™Extensively Evaluated

• > 100 published studies • 23 distinct peer-reviewed journals• Health Economic Studies

– AHCPR– Hutchinson– ScHARR

• Three meta-analyses– Bernstein– Abulafia– Klinkhamer

Conventional vs. LBC in Scotland

Conventional (%)

LBC

(%)

Unsatisfactory 13.6 1.9

Negative 80.9 91.7

Borderline 2.5 2.6

Mild 2.0 2.3

Moderate 0.6 0.8

Severe 0.4 0.6

Others 0.1 0.1

1 year conventional vs 1 year LBC

What is liquid based cytology?

Collection of cellular material into a vial

of preservative fluid

ThinPrep® 2000 Processor

ThinPrep® 3000 Processor

ThinPrep® ProcessIn the laboratory

1. Dispersion 2. Cell Collection 3. Cell Transfer

Conventional ThinPrep®

The Difference is Obvious

The ThinPrep® PapTest™

PAUL SULTANA

MLSSaturday 22 April 2023