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LBC: what changes can we expect in general practice?

Jacky Ollington
RGN FPCert
Practice Nurse
The Jubilee Street Practice
London
E:jacky@ollington.freeserve.co.uk

Since the introduction of the NHS Cervical Screening Programme (NHSCSP) in 1988, the death rate from cervical cancer in the UK has fallen by over 40%,(1) and currently stands at around 1,200 deaths a year in England and Wales.(2) With the aim of further reducing this mortality rate, the traditional cervical screening tool, the Pap test, is be replaced by the more reliable liquid-based cytology (LBC) test. This will be achieved in a rolled-out national programme, which is expected to take up to five years. Implementation will, in the main, be managed at local level.
How this is to be introduced to primary care and general practice is, as yet, uncertain, but undoubtedly it will demand many hours of reorganisation and retraining. This article takes a look at the benefits of this new method and the practicalities of implementation.

Benefits of LBC
The benefits of converting to LBC should include a significant reduction in the number of "inadequate" smears, along with fewer "false-negative" and "false-positive" results. Here we take a closer look at just what these terms mean.

Inadequate results
The Pap test was often cited as providing inadequate results. This refers to an inability to interpret the cellular material present on the slide, usually due to debris such as polymorphs, blood and mucus. Inadequate results can also be due to administrative errors.
With the Pap test, inadequacy rates can be as high as 17% or more, although the national average is thought to be around 9%.(2) This should fall to between 1% and 2% with LBC.(3)
This anticipated reduction in the number of inadequate results will be mostly down to how cervical cells are collected and retained during the new smear procedure (see Box 1).
With the new screening method, there is likely to be a sharp but transient increase in administrative errors, as is usual when any new system is introduced. Thorough training in the use of LBC should minimise these administrative inadequate results. In the longer term, fewer inadequate results will have a positive effect on general-practice targets, as these results are excluded from audit figures.

False-negative results
This refers to a failure to detect dyskaryosis (an abnormality of the cell nucleus) when it is present (ie, the test reports a positive/abnormal smear as negative/normal).
When discussing false-negative results it is important not to be misled! Many people talk about the failure of the Pap test to detect cervical cancer, but the smear test actually detects dyskaryosis and not cancer.(4)
However, false-negative results are still a problem. They are estimated to be as high as 30%,(5) and are thought to be caused by poor sampling technique. However, this does raise the question that if most false-negative results are caused by user error, what guarantee do we have that there will not be similar problems with LBC? For this reason, good training in the new technique is essential in order to minimise sampling errors. Studies have shown that LBC is significantly more sensitive in detecting dyskaryosis than the Pap test,(6) and therefore it should reduce the number of abnormal smears that are missed.

False-positive results
This refers to an inability to distinguish between dyskaryosis and other, nonharmful cellular changes - that is, the test reports a negative/normal result as a positive/abnormal one.
False-positive results are estimated to make up  around 6.5% of Pap test results,(2) and most commonly occur in women under the age of 25 years.(4) These false-positive results are thought to be because of the increased susceptibility to change of the cervical cells within this age group. The advantage of LBC is that it is thought to be much more effective in detecting actual dyskaryosis (rather than other cellular changes) than the Pap test; in other words, LBC has a greater level of specificity. Fewer false-positive results should mean fewer unnecessary interventions and less treatment for these younger women.

Implementation
The practicalities of implementing LBC could prove challenging. There will almost certainly be a period of overlap, even at practice level, whereby some ­smear ­takers will still be using the Pap test, while others will have been trained in and using LBC. This may result in a two-tier service and could be difficult to manage, particularly as some women may feel they are receiving ­second-rate care. How successfully this is dealt with will largely be down to how well the implementation of LBC is managed at local level. There will be practical issues to deal with, such as disposal of old and ordering of new stock. Transportation of specimens will need consideration as LBC is likely to be far more bulky to transport than the current Pap slides.(7)
The introduction of LBC may well be poorly received by clinicians in general practice and could be perceived as "yet another change", particularly when many practices are still struggling to meet the demands of the recent GMS contract.

Conclusion
In the long term, in line with the aims of the NHSCSP, there should be a reduction in the morbidity and mortality rates associated with cervical cancer. It is expected that there will be a quicker turnover of smear results in the laboratories with LBC, which will mean not only that women with abnormal smear results will receive speedier interventions, but also that women as a whole will receive smear results much quicker. General practice may not see a noticeable difference in workload with smear taking, but screening should be more efficient, with fewer smears to repeat and greater and more accurate detection of dyskaryosis. Smear takers should be prepared to promote LBC as the new improved screening tool that it appears to be.  

References

  1. National Health Service. NHS Cancer Screening Programmes. Cervical cancer incidence, mortality and risk factors. Available from URL: http://www.cancerscreening.nhs.uk/ cervical/risks.html
  2. National Institute for Clinical Excellence. Guidance on the use of liquid-based cytology for cervical ­screening. London: NICE; 2004. Available from URL: http://www.nice. org.uk/article.asp?a=1864
  3. National Health Service. NHS Cancer Screening Programme. Liquid-based cytology (LBC). Available from URL: http://www.cancerscreening.nhs. uk/cervical/lbc.html
  4. National Health Service. NHS Cancer Screening Programme. About the NHS cervical screening programme. Available from URL: http://www.cancerscreening.nhs.uk/cervical/index.html
  5. McNeeley S. New cervical cancer screening techniques. Am J Obstet Gynecol 2003;189(4):40-1.
  6. Huff B. Screening for cervical cancer: it's time to check your ­technique. AWHONN Lifelines 2000;4(3):53-5.
  7. Shaw A. The effectiveness of NHS cervical screening. Nurs Times 2002;98(24):32-4.

Resources
NHS Cancer Screening Programmes
This includes implementation guidelines
W:www.cancerscreening.nhs.uk

National Institute for Clinical Excellence
W:www.nice.org.uk

Trial Of Management of Borderline and Other Low-grade Abnormal smears (TOMBOLA)
W:www.tombola.ac.uk