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					Cervical screening
   Tim Wright Sept 07
  What who when
  Benefits (evidence)
  Cost
  Does it fit wilson’s criteria?
What, Who, When
    The NHS Cervical Screening Programme was set up
     in 1988 when the Department of Health instructed all
     health authorities to introduce computerised call-
     recall 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
    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
    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?
    Peto J, Gilham C, Fletcher O, Matthews FE. The cervical cancer
     epidemic that screening has prevented in the UK. Lancet
    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?
    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?
    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?
    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

                    3-yearly       5-yearly
                   screening      screening

   20-39 years        41%           30%

   40-54 years        69%           63%

   55-69 years        73%           73%
Cost of cervical screening
    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
    the condition should be an important health problem
    the natural history of the condition should be
    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
    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
  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?