Cervical Cervical screeningscreening

Tim Wright Sept 07Tim Wright Sept 07

IntroductionIntroduction

What who whenWhat who when Benefits (evidence)Benefits (evidence) CostCost Does it fit wilson’s criteria?Does it fit wilson’s criteria?

What, Who, WhenWhat, Who, When

The NHS Cervical Screening Programme was set up The NHS Cervical Screening Programme was set up in 1988 when the Department of Health instructed all in 1988 when the Department of Health instructed all health authorities to introduce computerised call-health authorities to introduce computerised call-recall systems and to meet certain quality standardsrecall systems and to meet certain quality standards

However, cervical screening began in Britain in the However, cervical screening began in Britain in the mid-1960s. By the mid-1980s many women were mid-1960s. By the mid-1980s many women were having regular smear tests, but there was concern having regular smear tests, but there was concern that those at greatest risk were not being tested, and that those at greatest risk were not being tested, and that those who had positive results were not being that those who had positive results were not being followed up and treated effectively.followed up and treated effectively.

What, Who, WhenWhat, Who, When

The programme screens almost four million The programme screens almost four million women in England each year. Of the women women in England each year. Of the women in the target age group most are tested in the target age group most are tested following an invitation and the rest were following an invitation and the rest were screened opportunistically. Some women screened opportunistically. Some women have more than one test during the course of have more than one test during the course of a year so that nearly four and a half million a year so that nearly four and a half million smears are examined by pathology smears are examined by pathology laboratories every year.laboratories every year.

What, Who, WhenWhat, Who, When A smear of cervical cells is examined for signs of dyskaryosis A smear of cervical cells is examined for signs of dyskaryosis

which if present indicate pre-malignant CIN.which if present indicate pre-malignant CIN. All women between the ages of 25 and 64 are eligible for a All women between the ages of 25 and 64 are eligible for a

cervical screening test every three to five years.cervical screening test every three to five years. Frequency of screening Frequency of screening Age group (years)Age group (years) First invitationFirst invitation 2525 3 yearly 3 yearly 25 – 4925 – 49 5 yearly5 yearly 50 – 6450 – 64 Only screen those who Only screen those who 65+65+

have not been screened have not been screened since age 50 or have had since age 50 or have had recent abnormal testsrecent abnormal tests

Is cervical screening Is cervical screening effective?effective?

PetoPeto J, J, Gilham Gilham C, Fletcher O, Matthews FE. The cervical cancer epidemic that C, Fletcher O, Matthews FE. The cervical cancer epidemic that screening has prevented in the UK. screening has prevented in the UK. LancetLancet 2004;364:249-256. 2004;364:249-256.

This study used the number of cervical cancer deaths from 1953 This study used the number of cervical cancer deaths from 1953 to 1987 to predict what future death rates would have been had to 1987 to predict what future death rates would have been had national screening not been introduced in 1988. This predicted national screening not been introduced in 1988. This predicted rate was compared with the actual rates of mortality from 1988 rate was compared with the actual rates of mortality from 1988 to 2002. to 2002.

The authors concluded that up to 5000 deaths per year are The authors concluded that up to 5000 deaths per year are likely to have been prevented by screening at a cost per life likely to have been prevented by screening at a cost per life saved of about £36,000.saved of about £36,000.

Is cervical screening Is cervical screening effective?effective?

BMJBMJ 20032003;326:901 ( 26 April ) ;326:901 ( 26 April ) Outcomes of screening Outcomes of screening to prevent cancer: analysis of cumulative incidence to prevent cancer: analysis of cumulative incidence of cervical abnormality and modelling of cases and of cervical abnormality and modelling of cases and deaths prevented. A E Raffledeaths prevented. A E Raffle, , B AldenB Alden, , M QuinnM Quinn, , P P J BabbJ Babb, , M T BrettM T Brett, ,

This study analysed screening records from 348 419This study analysed screening records from 348 419

women screened from 1976women screened from 1976  to 1996, and modelled cases to 1996, and modelled cases of cervical cancer and deaths withof cervical cancer and deaths with and withoutand without screening. screening.

It concluded that For every 10 000 women, in the absence It concluded that For every 10 000 women, in the absence of screeningof screening 80 women would be expected to develop 80 women would be expected to develop cancer of the cervix bycancer of the cervix by 2011, of whom 25 would die. With 2011, of whom 25 would die. With screening 10 of these deathsscreening 10 of these deaths would be avoided. would be avoided.

Is cervical screening Is cervical screening effective?effective?

80% of high grade dyskaryosis and of high80% of high grade dyskaryosis and of high

grade dysplasia would not progress to cancer.grade dysplasia would not progress to cancer. In the NHS cervical screening programme In the NHS cervical screening programme

around 1000 women need to be screened for around 1000 women need to be screened for 35 years to prevent one death35 years to prevent one death

For each death prevented, over 150 women For each death prevented, over 150 women have an abnormal result, over 80 are referred have an abnormal result, over 80 are referred for investigation, and over 50 have treatment.for investigation, and over 50 have treatment.

Is cervical screening Is cervical screening effective?effective?

Br J Cancer. 2003 Jul 7;89(1):88-93.Br J Cancer. 2003 Jul 7;89(1):88-93. Benefit of cervical Benefit of cervical screening at different ages: evidence from the UK audit of screening at different ages: evidence from the UK audit of screening histories.screening histories.

Sasieni PSasieni P, , Adams JAdams J, , Cuzick JCuzick J.. Screening histories of 1305 women aged 20-69 Screening histories of 1305 women aged 20-69

years, diagnosed with frankly invasive cervical years, diagnosed with frankly invasive cervical cancer and 2532 age-matched controls were cancer and 2532 age-matched controls were obtained from UK screening programme databases. obtained from UK screening programme databases. Data were analysed in terms of time since last Data were analysed in terms of time since last negative, and time since last screening smear.negative, and time since last screening smear.

Percentage of Cancer PreventablePercentage of Cancer Preventable(Protection offered by a single negative (Protection offered by a single negative smear)smear)

3-yearly 3-yearly screeningscreening

5-yearly 5-yearly screeningscreening

20-39 years20-39 years 41%41% 30%30%

40-54 years40-54 years 69%69% 63%63%

55-69 years55-69 years 73%73% 73%73%

Cost of cervical screeningCost of cervical screening

Money - Money - including the cost of treating cervical including the cost of treating cervical abnormalities – it has been estimated to cost around abnormalities – it has been estimated to cost around £157 million a year in England£157 million a year in England

Resources – Over 100,000 people are involved in Resources – Over 100,000 people are involved in cervical screening, including the doctors and nurses cervical screening, including the doctors and nurses who take the smears, the laboratory staff who review who take the smears, the laboratory staff who review the smears and the administrators who run the the smears and the administrators who run the computer systems.computer systems.

Harm – Discomfort, anxiety, time cost to the patients Harm – Discomfort, anxiety, time cost to the patients of smears, colposcopy, treatment.of smears, colposcopy, treatment.

Wilsons criterior and Wilsons criterior and Cervical ScreeningCervical Screening

the condition should be an important health problem the condition should be an important health problem the natural history of the condition should be the natural history of the condition should be

understood understood there should be a recognisable latent or early there should be a recognisable latent or early

symptomatic stage symptomatic stage there should be a test that is easy to perform and there should be a test that is easy to perform and

interpret, acceptable, accurate, reliable, sensitive and interpret, acceptable, accurate, reliable, sensitive and specific specific

there should be an accepted treatment recognised for there should be an accepted treatment recognised for the disease the disease

treatment should be more effective if started early treatment should be more effective if started early there should be a policy on who should be treated there should be a policy on who should be treated diagnosis and treatment should be cost-effective diagnosis and treatment should be cost-effective case-finding should be a continuous processcase-finding should be a continuous process

Wilson’s criteria and Wilson’s criteria and cervical screeningcervical screening

Natural history not clearly Natural history not clearly understood and ‘latent phase’ not understood and ‘latent phase’ not clearly defined. Up to 80% of clearly defined. Up to 80% of severe dyskaryosis dose not severe dyskaryosis dose not progress to Ca.progress to Ca.

Are smear tests acceptable?Are smear tests acceptable? Is is cost effective?Is is cost effective?