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Cervical screening - results

This page presents detailed cervical cancer screening statistics for England from the NHS Cervical Screening Programme Review 2006 including number of smears taken, smear results, outcome of referrals for smears and potential effect of screening. A short  summary of cervical screening statistics in England for 2007-2008 is also available.

It also includes a short section on the administration and results for cervical cancer screening programmes in Wales, Scotland and Northern Ireland. This information is based on the CancerStats report - Cervical Screening - UK published in 2003.

Cervical screening in England 1

On the NHS Cervical Screening Programme website you can read the Statistical Bulletin from the Cervical Screening Programme 2008. The following information is based on the 2003 CancerStats report Cervical Cancer Screening - UK.

 

Number of smears taken

The total number of cervical cancer smears examined in England during 2001-2 was 4,371,561. This figure includes smear tests taken from well women for screening purposes, repeat surveillance smears and symptomatic smears.

This total represents the results for approximately 3.9 million women, 3.8 million of whom were in the target age range 20-64.

About 71% of these women (2.7 million) were screened as a result of an invitation from the health authority. The remaining 1.1 million women were screened either opportunistically or as a result of a GP invitation.

The majority of smears examined were taken in the primary care setting ( Table 3.1).

Table 3.1: Percentage and number of smears examined by source of smear, England 2001-2002

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Cervical smears which were taken in the GP practice or other NHS community clinic from women aged 20-64 (and therefore most closely reflect the smears taken as part of the NHS cervical cancer screening programme) accounted for 3.9 million tests.

 

Smear results

Of the 4.4 million smears examined in England in 2001-2, 9.2% were inadequate (Table 3.2).

The proportion of inadequate cervical smears has increased each year from around 6% in 1990 to the level observed in recent statistics, although there has been a slight decrease in the latest data.The range between regional health authorities was 7.2% to 10.8%.

Three laboratories were participating in the Liquid Based Cytology (LBC) pilots and all of these laboratories had a lower percentage of inadequate smears than those shown in Table 3.2.

Table 3.2: Percentage of results of smear tests from GP and Community clinics*, women aged 20-64, England 2001-2002

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Table 3.2 also shows the percentage of results of adequate smear tests for women in the cervical cancer screening programme target age range. Of the adequate smears, 92.5% were negative and 7.5% were abnormal.

Figure 3.1 shows the proportion of adequate cervical cancer smears that are abnormal, by age.

It can clearly be seen that younger women have a higher proportion of abnormal smears and this proportion declines with increasing age. The majority of abnormal smears are due to borderline changes, mild and moderate dyskaryosis: only 0.6% of smears show severe abnormalities.

Figure 3.1: Abnormal test results, by age England 2001-2002

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Outcome of referrals for smears

Between April and June 2001, 32,634 women in England were referred to gynaecology, including colposcopy clinics. 14,636 (45%) of these referrals were as a result of a cervical smear test showing a potentially significant abnormality (moderate dyskaryosis or worse) and 17,998 (55%) followed persistent non-negative smears.

The outcomes for the two types of referrals are quite different, the cancer detection rate and the proportions found to have CIN2 or CIN3/carcinoma in situ are significantly higher in those referred after a single occurrence of a potentially significant abnormality.

For example, in women referred after a test indicative of moderate dyskaryosis or worse, 2.2% were found to have cancer and 71% CIN2 or CIN3/carcinoma in situ. This compares with 0.1% with cancer and 17% with CIN2 or CIN3/carcinoma in situ in women referred after persistent non-negative smears.

This indicates that the natural history of these two presentation groups is probably different.

 

Potential effect of screening

If screening for pre-malignant cervical lesions is effective, we could expect to see an increase in carcinoma in situ rates, a progressive decrease in cancer registrations and, finally, a reduction in mortality due to cervical cancer.

Registrations of carcinoma in situ

Trends in new cases of carcinoma in situ (CIS) need to be treated with caution for the following reasons.

Registration rates for CIS are not true incidence rates, (defined as number of new cases arising per head of population per year). As women are not screened annually, registration rates are a mixture of prevalence rates (for women being screened for the first time) and cumulative incidence rates from the date of last screen for women who have previously attended for cervical screening.

Also, CIS is asymptomatic and therefore cases can only be detected by screening. An increase in screening activity would then lead to an increase in registrations.

It has been shown that the registrations of CIS have broadly increased in line with the increase in the number of smears being undertaken.2

However, it can be seen from Figure 3.2 that since 1987 there has been a steady rise in CIS registrations in women aged 20-24 and 25-29, and an increase in women aged 30-34 since 1992, with no corresponding increase in the other age bands.

The large increase in registrations that is visible in 1984 is due to the inclusion of CIN3 in the CIS registrations for the first time.

Figure 3.2 : Age specific registrations of in situ cervical cancer in women aged 20-54, England and Wales 1971-98

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Invasive cervical cancer

Figure 3.3 shows the age specific incidence rates of invasive cervical cancer in Great Britain.

Prior to 1990 there was little change in the rates in women aged over 55. However, the incidence in the 45-54 age group decreased from 38.8 per 100,000 in 1971 to 22.3 per 100,000 in 1989. During the same time period there was an increase in incidence from 8.9 to 14.2 per 100,000 in women aged 15-44.

Figure 3.3: Cancer of the cervix uteri incidence rates per 100,000 women, England and Wales, 1971-98

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After 1990 the incidence of cervical cancer in all age groups have shown a decrease. This could correspond to the increased number of women that were found to have CIN3 or CIS in the late 1980s and were successfully treated and subsequent development of invasive disease was prevented.

Cervical cancer mortality

Age standardised mortality from cervical cancer has been falling since the 1950s. However, the rate of the decrease was around 1% a year until 1988 and then it accelerated to around 7% a year.

This sudden fall coincided with the improvements in the call-recall system.3

The age standardised mortality from cervical cancer hides differing patterns of age-specific mortality. As shown in Figure 3.4, in all groups except the youngest group, mortality was lower in 2000 than it was in 1971. The largest decreases since 1988 have occurred in women aged 55-64 and 65-74.

Figure 3.4: Cervical cancer mortality, England and Wales, 1971-2000

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A recent paper estimated that cervical cancer screening has saved over 8,000 lives between the introduction of the computerised call-recall system (1988) and 1997. It also showed that prior to the mid-1980s there were no significant mortality trends that could not be explained in terms of a birth cohort effect, but since then, mortality had significantly fallen each year.4

 

Cervical screening in Wales

On the Cervical Screening Wales website you can read the Statistical Review for 2006.

The following information is based on the CancerStats report Cervical Cancer Screening - UK published in 2003.

Cervical Screening Wales (CSW) is an organisation which was formed on 1st April 1999. It is responsible for the NHS cervical screening programme for women resident in Wales. Prior to the introduction of CSW there was no single coordinated cervical screening programme in Wales, with screening being operated independently by each health authority.

The programme targets women aged 20-64 and operates a standard three year recall interval across Wales.

Key facts 5 :

  • In 2000/01, 81% of all eligible women (aged 20-64 years) had been screened at least once in the previous 5 years.
  • During the year 2000/01 just over 210,000 women had a cervical smear test. 79% of these women were screened after receipt of a formal invitation, the remaining 21% were screened opportunistically.
  • 220,000 smears were examined in this year. 7.9% of results were inadequate, and there was wide variation between laboratories (range 5.9% to 11.0%)
  • Of the adequate smears, 92% were normal.
 

Cervical screening in Scotland

On the Information and Statistics Division website you can find the uptake of cervical screening in Scotland.

The following information is based on the CancerStats report Cervical Cancer Screening - UK published in 2003 .

The Scottish Cervical Screening Programme was introduced from 1989 and was fully established by 1993. Women aged 20-60 are invited at least once every five years, although in practice the programme is currently operating a three-year recall throughout Scotland.

The programme is coordinated centrally by the Scottish Screening Programmes Central Coordinating Unit, which took on this responsibility in 1996.

Key facts 6:

  • In 2000/2001, 86.5% of all eligible women had been screened in the past 5.5 years. (Figures do not include data for Lothian Health Board, which are unavailable)
  • In the year ending 31 March 2001, a total of 331,218 women in the target age range had a cervical smear test.
  • During the year ending 31 March 2001 (latest available data), the number of smears examined at laboratories in Scotland was 457,774. 8.5 % were inadequate.
  • 92.0% of adequate smears were reported as normal.
 

Cervical screening in Northern Ireland

On the Northern Ireland Cancer Screening Programmes website you can read the Cervical Screening Statistics for Northern Ireland.

The following information is based on the CancerStats report Cervical Cancer Screening - UK published in 2003.

Cervical screening is offered to women aged 20 to 65 in Northern Ireland. The programme operates a five year recall interval although many GPs run their own recall at an interval of three years.

Key facts 7:

  • Currently, coverage ranges between 70% and 75%.
  • In 2001 136,545 smears were examined. 8.4% of results were inadequate, and required a repeat smear
  • Of the adequate smears, 89.8% were normal.

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References for cervical screening programme results

  1. Government Statistical Service, Cervical screening programme, England 2001-02, in Statistical Bulletin 2002/21,. 2002: London.
  2. Quinn M, et al. The effect of screening on the incidence of and mortality from cancer of the cervix in England: evaluation based on routinely collected statistics. British Medical Journal, 1999. 318: p. 904-908
  3. Sasieni P, Cuzick J, Farmery E. Accelerated decline in Cervical cancer mortality in England and Wales. The Lancet, 1995. 346:
  4. Sasieni P, Adams J. Effect of screening on cervical cancer mortality in England and Wales: analysis of trends with an age period cohort model. BMJ, 1999. 318(7193): p. 1244-1245
  5. Cervical Screening Programme, Cervical Screening Wales Statistical Report 2000/2001 KC53/61. 2002. p.
  6. Thomson G, Personal communication, 2002.
  7. Murphy J, Personal communication. 2002.
Updated: 9 October 2009