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Liquid-based cytology: where are we now?

Maggie Cooper
RGN DiPN
Screening Programmes Manager
Surrey PCT

Freelance Nurse Trainer
Women's health

Liquid-based cytology (LBC) went through a rigorous validation process in the UK before introduction, and in October 2003 the National Institute for Health and Clinical Excellence (NICE) recommended that it became the standard method for taking a cervical sample.(1)
The implementation is now underway across the UK, with many places fully converted to the new technology. Scotland and Wales transferred to LBC very quickly once the decision to move to LBC was made. Both countries have much smaller populations and considerably fewer cytology laboratories and associated primary care staff than England - Scotland has 12 cytology laboratories compared with England's 134 labs.(2) Both the Northwest and East Midlands regions were early implementers in England.(3) London region completed conversion to LBC within the past few weeks; a considerable achievement with 21 labs to convert and well within the five-year period recommended by NICE.(1) Other parts of England have still not fully implemented; all the regions are partly converted but primary care trust (PCT) priorities vary - business plans have sometimes not been written or may have missed the financial planning that all PCTs carry out annually, and additionally massive reorganisation is taking place in many trusts. The NICE deadline is October 2008 so time is limited.

What is LBC?
In terms of improvement to the public health, cervical screening has proved to be a highly effective test, particularly since the computerised call and recall system was introduced in 1988. There has been a notable reduction in both incidence and mortality from cervical cancer since women have been identified and invited via GP registration systems, known as Exeter.(4,5) In spite of this ongoing success many women have reservations and anxieties about the test.
The conventional cervical smear technique (PAP) has remained much the same from the time it was introduced in the last century. Many women find it an uncomfortable process and often ask when it will be updated. Unfortunately the means of accessing the cervix remains the same with LBC, although LBC has many other advantages. Probably the most important of these is human papilloma virus testing, which was part of the English LBC implementation study and is another area of development that could improve the management of cervical abnormalities, especially in older women. The ARTISTIC trial (A Randomised Trial of HPV Testing in Primary Cervical Screening) is considering whether HPV testing would add effectiveness into the cervical screening programme.(6)
Practice nurses take the majority of smears/samples in general practice. This is partly due to reorganisation of work patterns in general practice and partly patient choice.

How is the LBC sample taken?
The sample is still taken using a speculum for access and visibility. Instead of using the wooden Aylesbury spatula, scraping the cells from the surface of the ectocervix, spreading them onto a slide and then fixing them with an alcohol solution, the nurse uses a Cervex Brush and collects the sample (no longer a smear) into a vial of preservative fluid. The Cervex Brush is a multi-fronded sampling device that picks up large numbers of cervical cells. The nurse passes the speculum, visualises and assesses the cervix and then takes the sample by firmly rotating the Cervex Brush FIVE times in a clockwise direction, using the same pressure as with the Aylesbury spatula.
From this point, there are practical differences depending on which company's product is used. Although NICE approved LBC, they found that only two products had sufficient performance data for review - the ThinPrep Pap Test from Cytyc and the Surepath LBC distributed by Medical Solutions in the UK (see Figures 1 and 2).

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With the ThinPrep Pap Test, a 20 ml vial of preservative fluid is provided, into which the nurse rinses the Cervex Brush. The brush is vigorously agitated in the preservative at least 10 times, ensuring that as many cells as possible are transferred to the preservative. The vial is then capped, labelled with patient details and sent to the laboratory for interpretation.
The Surepath system requires the nurse to remove the head of the Cervex Brush and place it into the collection vial containing 10 ml of a different preservative fluid. The vial is then capped and shaken before despatch to the laboratory with appropriate patient details added.
Both samples must be accompanied by a request form, with the appropriate clinical and personal details.(7)
Both methods are equally easy to use for the sample taker and are both quicker and somehow cleaner to carry out.

How does it work?
Once the sample reaches the laboratory it is processed and a slide is produced for analysis by a cytologist. The sample is mixed to disperse the cells in the fluid. Cellular debris, such as blood and mucus, is largely removed and a thin layer of cells is deposited onto a microscope slide. Each slide contains a subsample of cells in a standard circular format, rather than the random spread of cells produced in conventional smears. There are differences in processing methods between the two companies currently providing LBC equipment.

How does LBC benefit women?
There are a number of improvements from the introduction of LBC into the cervical screening programme, which will be of benefit to both women and to those who take the sample.

Inadequate or unsatisfactory samples
Data from the English LBC Pilot Study showed a consistent fall in the inadequate rate with the introduction of LBC across the three pilot sites.(8) This dramatic decrease in inadequate/unsatisfactory samples has been replicated wherever LBC has been introduced and remains low. There is some concern that the rate is now too low and work is underway to provide a standard across the UK whereby lab staff will have an objective benchmark against which to measure each sample.
Monitoring of results by sample takers should be an ongoing process - first, to ensure that the laboratory receives all the samples sent and returns a result to the practice; and second, to make sure that the results fall within the parameters set both locally and nationally. Many practitioners are now finding that an unsatisfactory sample is a rare event.
Before the introduction of LBC the UK inadequate rate was between about 6% and 13% and in areas where there is full conversion it has now fallen to less than 2% (see Figure 3).(2)

[[nip37_fig3_76]]

Improved detection of precancerous abnormalities
The aim of the cervical screening programme is to reduce the incidence and mortality from cervical cancer in the screened population.(4)
The rationale for the test is that abnormalities can be detected and treated at an early stage, thus preventing the need for major surgery and sometimes associated problems. It must be made clear to women that no screening test is 100% effective but is extremely worthwhile. The idea that disease may be missed by either the smear taker and/or the laboratory is not well understood or accepted by women. In other health areas results are more finite and the concept of a test being rather less than 100% reliable is difficult to grasp. Data from the UK pilot study demonstrated a small increase in the sensitivity of the test and current figures from UK laboratories converted to LBC replicate this improved sensitivity.(8) Most of these findings are as yet unpublished or have only been presented at conferences, but in a paper published in Cytopathology in April 2006 a rise in all grades of abnormality since LBC was introduced was demonstrated.(9) This data has been replicated by other laboratories and may in part be due to the lack of obscuring material on LBC slides.

Faster results
National guidance for smear turnaround times states that 80% of smears taken should be returned to women within four weeks and 100% within six weeks.(10) Smear turnaround times are monitored by quality assurance teams across England and are deemed to be important quality indicators. Before the introduction of LBC, many laboratories failed to meet the standards. There has been a huge improvement in the timely turnaround of results with LBC - many labs are able to return results within two to three weeks, a great improvement for women.

Decreased anxiety for women
Although anxiety and stress are not easily measurable in this context, they should not be dismissed as unimportant. Women may be anxious about attending for a cervical sample for a number of reasons.(11) These can strongly influence a woman's decision to continue with cervical screening and can make the job of the smear taker more challenging. The dramatic reduction in inadequate and equivocal results should help to decrease some of the anxiety associated with cervical screening.

What it means for practice nurses and how it could change their practice
An LBC training document was produced from the findings of the LBC pilot study and published on www.cancerscreening.nhs.uk in order to achieve consistency and effectiveness with the roll-out of primary care training across the UK.(12) Large-scale implementation of the process was viewed as an opportunity to update all existing sample takers, as practical training was deemed to be vital for a successful roll-out. The three suggested options were:

1. Formal training: 1-2-hour workshop to be attended by at least one GP and practice nurse from each surgery and staff from community clinics
A nurse trainer, local cytologist and perhaps a representative from the company providing the equipment (always useful for the technical questions), usually share the formal training.
Groups of up to 30 are ideal so that interaction and discussion can take place; this can be a good time to update other cervical screening topics. It is not essential that all sample takers attend a formal session as demonstrated in the data produced from the UK pilot study, but perhaps in some areas it is necessary, eg, where basic and update training has not been provided regularly.(8) Locums, associates and agency staff should be included as these are practitioners who can slip through the net.

2. Cascade training within practice/clinic by an experienced smear taker (GP or nurse or both) who has attended the formal training
In practices where a representative from the practice has attended the formal training, cascade training must follow for those who were unable to attend the formal session. This takes place back at the practice, and this is one area where the experienced smear taker can further her role within practice.

3. Practice-based training where an experienced trainer from outside the practice would go in and deliver the session
Practice-based training is usually carried out by an "expert" nurse from outside the practice so does not provide the same opportunity for role enhancement. It can be useful in rural areas where there may be a reluctance to travel long distances for a short session. This method has not been widely used during the implementation process but was shown to be effective during the LBC pilot process.8 It is, however, labour intensive.
These training options can provide some excellent opportunities for practice nurses to take on the role as lead practitioners for cervical screening within their practice or local area. Many areas use LBC roll-out as the time to make changes and improvements to the local programme; for example to elect a screening lead in each practice or to allocate a personal code to each sample taker. The role of the screening lead is not an arduous task; rather the person becomes the point of contact within each practice for the PCT, laboratory, colposcopy and call and recall agency to deal with any issues or problems that arise within practice. Nurses are in an ideal position to take this role on; they are often the most well trained, competent sample takers within general practice as well as generally being the first choice for many women when accessing cervical screening. The cascade training back at the practice is an excellent way of stepping into that role or improving the practice nurse profile, and other screening issues can also be addressed at the same time.
It should be noted that basic training in cervical screening should take place before practice for all sample takers and following that update training is recommended at least once every three years.(13)

Conclusion
LBC will soon be fully implemented across the UK and in many cases can provide an excellent opportunity for practice nurses to enhance their role within practice.

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References

  1. NICE. Guidance on the use of liquid-based cytology for cervical screening. Technology Appraisal 69. London: NICE; 2003.
  2. The Information Centre. Cervical Screening England 2005-6. Available from: http://www.cancerscreening.nhs.uk
  3. NHS Cancer Screening Programmes. Available from: http://www.cancerscreening.nhs.uk
  4. NHS. Cervical screening. A pocket guide. London: NHS; 2004.
  5. Charles Kitchener H. ARTISTIC (A Randomised Trial of HPV Testing in Primary Cervical Screening). Academic Unit of Obstetrics and Gynaecology. University of Manchester. In progress - due to complete 2009. Available from: http://www.cancerscreening.nhs.org.uk
  6. Nursing and Midwifery Council. Guidelines for records and record keeping.  London: NMC; 2005.
  7. Moss SM, Gray A, Marteau T, Legood R, Henstock E, Maissi E. Evaluation of HPV/LBC cervical screening pilot studies. London: DH; 2004.
  8. Williams ARW. Liquid-based cytology and conventional smears compared over two 12-month periods. Cytopathology 2006;17:82-5.
  9. NHSCSP. Quality standards for cervical screening in the UK. NHSCSP Publication No. 3. January 1996.
  10. Yu CK, Rymer J. Women's attitudes and awareness of smear testing and cervical cancer. Br J Fam Plann 1998;23:127-33.
  11. NHSCSP. Training in taking samples for liquid based cytology. LBC Implementation Guide 4. May 2004.
  12. NHSCSP. Taking samples for cervical screening a resource pack for trainers. NHSCSP Publication No. 23. April 2006.

Resources
UK Cancer Screening Programmes
W: www.cancerscreening.nhs.uk
Includes Breast, Cervical and Bowel Cancer screening information. Publications free to health care professionals. Highly recommended

Cancerbackup
W: www.cancerbackup.org.uk
Cancer charity that produces some useful booklets intended for patients but also useful for nurses new to practice.
Reasonably priced

DIPEx
W: www.dipex.org.uk
Interactive website where patients describe their experiences of healthcare. Includes breast and cervical screening scenarios.