A brief history of the NHS cervical screening programme
This page presents information on informed choice, the role of human papillomavirus testing, liquid based cytology and the role of health authorities and primary care trusts. Organised cervical screening programmes have been in operation in parts of Europe and North America for over 30 years. Cervical screening has been shown to be effective in a number of countries, although not by means of randomised controlled trials.1
In England, cervical screening was introduced in 1964, and although a large number of smears were taken, it became obvious that the programme was not covering those women who were at greatest risk and some individuals with positive results were not followed up successfully.2
In 1988 the Department of Health issued a circular,3 requiring all district health authorities to introduce a computerised call-recall system and recommended that women aged 20 to 64 should participate in cervical cancer screening every 3 to 5 years.
The incidence of both carcinoma in situ and invasive cervical cancer is very low in women aged under 25. One of the principles of screening is that the condition to be screened for is an important health problem in the target population. As the disease is very rare in young women, population cervical screening of women aged under 25 is not justified.4,16
The importance of quality at all stages of the cervical screening programme: taking the smear, interpretation in the laboratory, follow up and organisation of the screening programme was emphasised in the 1988 health circular and in all subsequent guidelines.
Financial incentives for GPs were introduced in 1990 and have been successful in obtaining high coverage, although their introduction has not been without its critics.6
Most cervical screening is conducted using the Papanicolaou smear test, in which a sample of cells are scraped from the cervix at the junction between the endocervix (which is covered by columnar epithelium) and the ectocervix (covered by squamous epithelium). This area is known as the transformation zone and is shown in Figure 1.1.
The collected cells are smeared onto a slide, fixed and then sent to the laboratory for examination. Another method for obtaining a sample, liquid based cytology, is discussed below.
Depending on the persistence and degree of severity of dyskaryosis, women may undergo a further procedure called colposcopy to provide a histological diagnosis of cervical intraepithelial-neoplasia (CIN).
The links between dyskaryosis, CIN and management options are outlined in Table 1.1 and Table 1.2.
Until the late 1980s, cervical screening in England had been judged to be largely ineffective, in part due to the reasons outlined above. However, the incidence of cervical cancer and mortality from cervical cancer has been declining since the 1990s.
The cervical screening programme designed an information leaflet to ensure that women are told what screening can and cannot achieve.
The leaflet includes an explanation about false positive and false negative results, and addresses the need to inform patients about the use made of personal information for audit. This should enable women to make an informed choice based on an understanding about why they are attending for cervical cancer screening.7
By providing information about the limitations of the test, anxiety may be reduced in those women who are recalled for further investigations. The information is sent to all women in England with their invitation for cervical screening.
Infection with certain types of human papillomavirus (HPV), in particular HPV 16 and HPV 18 have been shown to be associated with development of cervical cancer and also of cervical intraepithelial-neoplasia (CIN).
Recently it has been shown that 99.7% of cervical cancers contain HPV DNA8 and it is thought that HPV infection is a necessary cause of cervical cancer. Studies have reported odds ratios for stage 3 cervical intraepithelial neoplasia or invasive cancer of 17-24 for women with a high risk of HPV infection of the cervix (and higher odds ratios if infected with HPV 16).9,11
HPV testing as a primary screening tool has a higher sensitivity for CIN than cytology (96% compared with 55% for CIN3 or higher and 96% compared with 53% for CIN2 or higher)but a lower specificity, especially in young women (under 30 years old) who tend to have transient HPV infections.12
A review13 of the role of HPV testing within cervical screening has concluded that the most plausible role of HPV testing in the NHS Cervical Screening Programme may be to guide the management of women with borderline or mildly dyskaryotic smears.
A pilot of high risk HPV type testing is being conducted in the cervical screening programme. Women who have borderline or mild dyskaryosis are being tested for high risk HPV (using the sample collected for cytology).
Following a report 15 from the National Institute for Clinical Excellence (NICE), liquid-based cytology is currently being rolled out across the NHS screening programme.
Liquid-based cytology (LBC) is a new way of sampling and preparing cervical cells. Using this technique, the cells collected from the cervix are placed in a preservative fluid that is then sent to the laboratory rather than being spread onto a slide.
At the laboratory the sample is mixed and treated to remove unwanted material, and then a thin layer of the cell suspension is placed on a slide for inspection. The remaining sample is then available for subsequent HPV testing, if required.
Where LBC is being implemented women are getting their results faster and it also reduces inadequate rates from an average of almost 10 percent to 1-2 percent.
Since the re-organisation of the NHS, the Primary Care Trusts (PCTs) are now responsible for commissioning the cervical screening programme and for ensuring women are properly called and recalled and given their results. They are also charged with achieving at least 80% coverage.
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- Sigurdsson K. The Icelandic and Nordic cervical screening programs: trends in incidence and mortality rates through 1995. Acta Obstet Gynecol Scand, 1999. 78(6): p. 478-85.
- Farmery E, Gray J. Report of the first five years of the NHS cervical screening programme, 1994, National Co-ordinating Network: Oxford.
- Department of Health and Social Services, Health Services Management: Cervical Cancer Screening, in Health Circular HC (88) 1, 1988.
- National Audit Office, Cervical and Breast Screening in England: a report by the Comptroller and Auditor General, 1992: London.
- National Audit Office, The performance of the NHS cervical screening programme in England: a report by the Comptroller and Auditor General, 1998: London.
- Anderson CM, Nottingham J. Bridging the knowledge gap and communicating uncertainties for informed consent in cervical cytology screening; we need unbiased information and a culture change. Cytopathology, 1999. 10(4): p. 221-8.
- NHS Cancer Screening Programme, Cervical Screening: the facts. ed., ed. Vol. 2001:
- Walboomers JMM, Jacobs MV, Manos MM. Human Papillomavirus is a necessary cause of invasive Cervical Cancer Worldwide. Journal of Pathology, 1999. (189): p. 12-19
- Peto J, Gilham C, Deacon J, et al. Cervical HPV infection and neoplasia in a large population-based prospective study: the Manchester cohort. BJC 2004;91(5):942-53.
- Olson AO. Human papillomavirus and cervical intraepithelial neoplasia grade II-III: a population-based case control study. Int J Cancer, 1995. 61: p. 312-315.
- van der Graaf Y, et al. Human papillomavirus and the long-term risk of cervical neoplasia. Am J Epidemiol, 2002. 156(2): p. 158-64
- Cuzick J, Clavel C, Petry KU, et al. Overview of the European and North American studies on HPV testing in primary cervical cancer screening. IJC 2006;119(5):1095-101.
- Cuzick J, Sasieni P, Davies P, et al. A Systematic Review of the Role of Human Papillomavirus Testing Within a Cervical Screening Programme. Health Technol Assess, 1999. 3(14):
- NHS Cancer Screening Programme, HPV Factsheets. Vol. 2002:
- NICE, Guidance on the use of liquid based cytology for cervical screening, 2000.
- Sasieni P, Adams J, Cuzixk J. Benefit of cervical screening at different ages: evidence from the UK audit of screening histories. Br J Cancer 2003; 89:88-93