Transcript Cervical screening

Cervical screening
Tim Wright Sept 07
Introduction
What who when
 Benefits (evidence)
 Cost
 Does it fit wilson’s criteria?
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What, Who, When
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The NHS Cervical Screening Programme was set up
in 1988 when the Department of Health instructed all
health authorities to introduce computerised callrecall systems and to meet certain quality standards
However, cervical screening began in Britain in the
mid-1960s. By the mid-1980s many women were
having regular smear tests, but there was concern
that those at greatest risk were not being tested, and
that those who had positive results were not being
followed up and treated effectively.
What, Who, When
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The programme screens almost four million
women in England each year. Of the women
in the target age group most are tested
following an invitation and the rest were
screened opportunistically. Some women
have more than one test during the course of
a year so that nearly four and a half million
smears are examined by pathology
laboratories every year.
What, Who, When
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A smear of cervical cells is examined for signs of dyskaryosis
which if present indicate pre-malignant CIN.
All women between the ages of 25 and 64 are eligible for a
cervical screening test every three to five years.
Frequency of screening
Age group (years)
First invitation
25
3 yearly
25 – 49
5 yearly
50 – 64
Only screen those who
65+
have not been screened
since age 50 or have had
recent abnormal tests
Is cervical screening effective?
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Peto J, Gilham C, Fletcher O, Matthews FE. The cervical cancer
epidemic that screening has prevented in the UK. Lancet
2004;364:249-256.
This study used the number of cervical cancer deaths from 1953
to 1987 to predict what future death rates would have been had
national screening not been introduced in 1988. This predicted
rate was compared with the actual rates of mortality from 1988
to 2002.
The authors concluded that up to 5000 deaths per year are
likely to have been prevented by screening at a cost per life
saved of about £36,000.
Is cervical screening effective?
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BMJ 2003;326:901 ( 26 April ) Outcomes of screening to
prevent cancer: analysis of cumulative incidence of
cervical abnormality and modelling of cases and deaths
prevented. A E Raffle, B Alden, M Quinn, P J Babb, M
T Brett,
This study analysed screening records from 348 419 women
screened from 1976 to 1996, and modelled cases of cervical
cancer and deaths with and without screening.
It concluded that For every 10 000 women, in the absence of
screening 80 women would be expected to develop cancer of
the cervix by 2011, of whom 25 would die. With screening 10 of
these deaths would be avoided.
Is cervical screening effective?
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80% of high grade dyskaryosis and of high grade
dysplasia would not progress to cancer.
In the NHS cervical screening programme around
1000 women need to be screened for 35 years to
prevent one death
For each death prevented, over 150 women have an
abnormal result, over 80 are referred for
investigation, and over 50 have treatment.
Is cervical screening effective?
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Br J Cancer. 2003 Jul 7;89(1):88-93. Benefit of cervical
screening at different ages: evidence from the UK audit of
screening histories.
Sasieni P, Adams J, Cuzick J.
 Screening histories of 1305 women aged 20-69 years,
diagnosed with frankly invasive cervical cancer and 2532
age-matched controls were obtained from UK screening
programme databases. Data were analysed in terms of time
since last negative, and time since last screening smear.
Percentage of Cancer Preventable
(Protection offered by a single negative
smear)
3-yearly
screening
5-yearly
screening
20-39 years
41%
30%
40-54 years
69%
63%
55-69 years
73%
73%
Cost of cervical screening
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Money - including the cost of treating cervical
abnormalities – it has been estimated to cost around
£157 million a year in England
Resources – Over 100,000 people are involved in
cervical screening, including the doctors and nurses
who take the smears, the laboratory staff who review
the smears and the administrators who run the
computer systems.
Harm – Discomfort, anxiety, time cost to the patients
of smears, colposcopy, treatment.
Wilsons criterior and Cervical
Screening
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the condition should be an important health problem
the natural history of the condition should be
understood
there should be a recognisable latent or early
symptomatic stage
there should be a test that is easy to perform and
interpret, acceptable, accurate, reliable, sensitive and
specific
there should be an accepted treatment recognised for
the disease
treatment should be more effective if started early
there should be a policy on who should be treated
diagnosis and treatment should be cost-effective
case-finding should be a continuous process
Wilson’s criteria and cervical
screening
Natural history not clearly understood
and ‘latent phase’ not clearly defined.
Up to 80% of severe dyskaryosis dose
not progress to Ca.
 Are smear tests acceptable?
 Is is cost effective?
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