Cervical screening Tim Wright Sept 07 Introduction 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 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? 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 smear) 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 Screening 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?