Jade and the dangers of smear testing
Cancer charities hope that ‘Jade’s legacy’ will be more uptake of cervical smear tests. This might not be a good thing.
The tabloid newspapers and cancer charities hope that ‘Jade Goody’s legacy’ will be increased public awareness of cervical cancer and more uptake of cervical smear tests amongst young women. The Sun is petitioning the government to lower the age of a woman’s first cervical screening to 20. The head of Cancer Research UK is pleased about the heighted awareness, arguing that it is ‘critical that young women take up their invitations to cervical screenings if we are to avoid more tragic cases like Jade’s’.
But won’t encouraging young women to fear that they have the disease increase the burden on the health services? And might more ‘awareness’ of cervical cancer – in other words, increased concern and possibly panic amongst young women – be a negative rather than positive thing?
Cancer of the cervix is a fairly rare form of cancer in Britain, accounting for less than half a per cent of cancer deaths and around four per cent of cancer cases in women. Deaths from cervical cancer slowly declined over the past 50 years, from 2,500 in 1950 to 1,150 in 1997 to 950 in 2006 (1). In 20 years as a GP I have had two patients who have died from cervical cancer, which is probably over the career average; typically, neither had ever had a smear test.
The smear test was introduced in Britain in the mid-1960s, following a famous study in British Columbia, Canada. This study appeared to show a dramatic reduction in cancer following the introduction of smear tests, which allowed the early detection and treatment of ‘pre-cancerous’ areas. There was considerable controversy at the time over whether the decline in death rate could be attributed to smear tests (it had declined elsewhere without such tests) and over whether cells labelled as ‘pre-cancerous’ might return to normal without treatment, rather than progressing to invasive malignancy.
In addition, smear tests failed to meet two of the standard criteria for screening programmes laid down by the World Health Organisation: cervical cancer is uncommon and its natural course is not well understood (2). Though many experts were sceptical, a powerful lobby of cancer specialists prevailed upon the UK Labour government to introduce a cervical smear service in 1966 (3).
Two years later, the eminent epidemiologist Archie Cochrane caused a furore when he claimed that there was no evidence that smears would reduce the death rate from cervical cancer. He particularly objected to the use of a screening test for a condition for which there was no effective treatment; an authoritative review in 1999 conceded that there had been ‘no significant improvements in treatment for cervical cancer over the past 20 years’ (more recently, however, a vaccine has been introduced for cervical cancer) (4). Reflecting some years later on the ‘uproar, abuse and isolation’ he experienced as a result of his questioning of the cervical smear programme, Cochrane commented that, because of the introduction of this programme without proper evaluation, ‘we would never know whether smears were effective or not’ (5).
In 1988, following criticisms of the haphazard character of the cervical smear system, a National Coordinating Network for the NHS Cervical Screening Programme was established. In 1990, the new contract imposed on GPs by the government offered substantial incentives, now worth millions of pounds each year, tied to smear rate performance targets. As a result of these measures, coverage of the target age group rose from 42 per cent in 1988 to 85 per cent in 1994, a level subsequently maintained (6). There was more controversy about cervical screening in the late 1990s. The claim by cancer specialist Brian M Quinn that in women under 55 ‘screening may have prevented 800 deaths in 1997’ was contested by surgeons Jayant S Vaidya and Michael Baum, who noted that the data presented could just as easily have been used to claim that screening caused a similar increase in mortality (7).
The contrast between the high level of public faith in the cervical smear programme and the private recognition among medical authorities of its unsatisfactory character is remarkable. In their reply to Vaidya and Baum, Quinn and his colleagues admitted that they remained ‘deeply concerned about the well-known problems with cervical screening’, which they listed:
article continues after advertisement
‘[C]ervical cancer is a comparatively rare disease and its natural course is not well understood; the smear test has both low sensitivity and low specificity; many tests are technically unsatisfactory and the proportion of such tests varies across the country; the mix of three-year and five-year screening intervals is inequitable; too many smear tests are opportunistic; and the programme costs four times as much as breast screening.’ (8)
The low sensitivity of the smear test means that many women have been diagnosed as having cervical cancer which had been missed on previous smears. The fact that some such cases have resulted in litigation has led to calls for doctors to make clear that smears may miss between five and 15 per cent of abnormalities and to ensure that patients are giving properly informed consent to this procedure (9).
The low specificity of the smear test means that it yields a relatively high proportion of false positive results: that is, it suggests that a woman has malignant or pre-malignant cells when more invasive procedures (involving the removal of a wider area of tissue in a ‘loop’ or ‘cone’ biopsy) confirm that this is not the case. In day-to-day practice, this is by far the biggest problem arising from smear tests, causing enormous anxiety and distress, often continuing for weeks or months pending delays in further investigations.
Bristol public health consultant Angela Raffle has noted the tendency of staff, in response to publicity over missed cases, to over-diagnose minor abnormalities (10). While patients suffered needless anxiety, staff lived in fear of failing to identify potentially malignant cases. As a result, ‘much of our effort in Bristol [was] devoted to limiting the harm done to healthy women and to protecting our staff from litigation as cases of serious disease continue to occur’. As Raffle recognised, many healthy women are left with worries about cancer and difficulties in obtaining life insurance. Those who receive treatment may experience considerable discomfort, bleeding and sexual problems – as well as long-term anxieties about fertility. Raffle said of her experiences in Bristol: ‘By offering screening to 250,000, we have helped a few, harmed thousands, disappointed many, used £1.5million each year, and kept a few lawyers at work.’ (11)
Meanwhile, women in that 10 to 15 per cent of the female population which has never had a smear, who are likely to be (like my two patients), older, poorer and from ethnic minorities, will ensure that the mortality figures remain fairly steady. Health promotion propaganda which characterises cervical cancer as a sexually transmitted disease (on the dubious grounds of an association with the wart virus) has undoubtedly deterred many women from having smear tests. Encouraging more and more young women to visit their doctors and demand a smear test: we should ask whether this is a ‘legacy’ of Jade Goody’s death that is worth preserving.
Dr Michael Fitzpatrick is author of The Tyranny of Health (Routledge), from which the above is an edited extract. (Buy this book from Amazon(UK).)
(1) ‘Effect of screening on incidence of and mortality from cancer of the cervix in England: evaluation based on routinely collected statistics’, M Quinn et al, British Medical Journal, 318: 904-8, 1999
(2) Principles and Practice of Screening for Disease, JMG Wilson and G Junger, World Health Organisation, 1968
(3) pp66-69, The Diseases of Civilisation, B Inglis, Hodder and Stoughton, 1981
(4) ‘Effect of screening on incidence of and mortality from cancer of the cervix in England: evaluation based on routinely collected statistics’, M Quinn et al, British Medical Journal, 318: 904-8, 1999
(5) ‘Some reflections’, A Cochrane, in A Question of Quality: Roads to Assurance in Medical Care, G McLachlan, OUP, 1976
(6) ‘Effect of screening on incidence of and mortality from cancer of the cervix in England: evaluation based on routinely collected statistics’, M Quinn et al, British Medical Journal, 318: 904-8, 1999
(7) ‘Screening and mortality from cervical cancer’, JS Vaidya and M Baum, British Medical Journal, 319:642, 1999
(8) ‘Effect of screening on incidence of and mortality from cancer of the cervix in England: evaluation based on routinely collected statistics’, M Quinn et al, British Medical Journal, 318: 904-8, 1999
(9) ‘Smear tests were not on trial but should have been’, CM Anderson 1999, British Medical Journal, 318: 1007; ‘Women must be given fully informed information about cervical screening’, J Nottingham, British Medical Journal, 318: 1555-6, 1999
(10) ‘Detection rates for abnormal cervical smears: what are we screening for?’, Lancet 345: 1469-73, Raffle et al, 1995
(11) ‘Informed participation is essential’, AE Raffle, British Medical Journal, 314: 1762-3, 1997