breastscreen aotearoa an independent review - Ministry of Health

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1. INTRODUCTION1.1 The benefit of mammography screening is a reduction in the risk of death frombreast cancer among women in the eligible age-range. Over the past 40 years therehave been a number of scientifically conducted trials in each of which women havebeen randomised to a study group who were offered screening or to a control groupwho were not. Meta-analyses of the results of these trials have shown that womenaged over 50 when first screened are 30% to 40% less likely to die from breast cancerthan women in the control group. This conclusion was challenged two years ago bystatisticians from Denmark, who questioned the validity of previous trials, andconcluded that benefit was unproven and that a much larger trial, individuallyrandomising hundreds of thousands of women was still needed, in order to reach aclear conclusion on whether mammography screening saves any lives. In response tothis hypothesis the World Health Organisation assembled a group of 25 experts inevaluation of screening to re-examine existing evidence. Their conclusion, to bepublished in a forthcoming monograph from the International Agency for Research onCancer, is that the original estimate of a 30% to 40% reduction in risk of death frombreast cancer is correct, and that therefore in populations where many women diefrom breast cancer a screening service is a valid public health measure. (IARCScientific Publications, Prevention Series, International Agency for Research onCancer, Lyon, France, in press).1.2 Hence New Zealand's decision to provide a national breast screening service,BreastScreen Aotearoa, is upheld by current evidence.1.3 The three principal factors influencing how much benefit can be obtained in anypopulation are the proportion of the eligible population who are screened, thesensitivity of the screening test (mammography) in detecting invasive cancers at astage when the cancer is still curable, and the adequacy of the treatment provided forscreen-detected cancers. A fourth possible but unproven benefit is the detection andtreatment of pre-invasive ductal carcinoma in situ, (DCIS). This is unproven becausealthough there is evidence that some cases of DCIS, particularly those withhistological high grade malignancy, progress to invasive cancer and their removalwould thus be of benefit, there may be others that would not become invasive withinthe woman’s lifetime. Thus while screening reduces a woman's risk of dying frombreast cancer by about 35%, it may at the same time increase a woman's risk of beingdiagnosed with in situ breast cancer.1.4 The principal human costs of the screening programme arise from the fact thatlike all screening tests mammography inevitably gives both false positive and falsenegative results. Women with false positive results have to go through the anxiety andinconvenience of being recalled for assessment, many have to undergo needle biopsyand a few open biopsy with consequent pain and morbidity. Women with falsenegative results undergo the stress associated with thinking they are clear of cancerand then finding they are not, and possibly some women may delay seeking diagnosisfor a breast symptom because they assume they are clear. Anger at finding an intervalcancer may lead some women to sue for compensation. As mentioned above, theidentification of DCIS may also cause harm by treating a woman as a breast cancer6
patient when she might not otherwise have developed invasive disease. There arevery substantial financial costs to the health service in providing screening, unlikely tobe compensated by reduced costs of treating advanced cancers. And for many womenthere are financial costs in attending for screening and assessment.1.5 In the main part of this report the performance of Breast Screen Aotearoa, (BSA),in its efforts to maximise the benefits and to minimise the costs is reviewed, togetherwith the systems in place for auditing and monitoring the programme. Myconclusions are based on a wealth of documents relating to BSA which I was sent inadvance of my visit, together with the impressions gained by visiting the screeningcentres and meeting with about 40 different groups of people concerned in one way oranother with BSA.2. BACKGROUND2.1 Following two pilot programmes, which had taken place in Waikato and Otagoand Southland between 1991 and 1996, a decision was made in 1995 to provide anational breast cancer screening service in New Zealand. The service, Breast ScreenAotearoa, (BSA), provides free two-yearly mammography for all New Zealandwomen between the ages of 50 and 64. Between 1996 and 1998 preparatory workwas done to develop a set of interim quality standards and a national monitoring andevaluation system. Regional Health Authorities tendered for selection of appropriateproviders of mammography screening and six Lead Providers were identified, locatedin centres which would cover the whole geographical spread of the population. Theyentered into contracts with the Health Funding Authority in late 1998 and are thusnow entering their fourth year of screening. Separate funding was made available toHospital & Health Services, (now District Health Boards) to refund them for the costsof treating women whose breast cancer was diagnosed by BSA. Separate contractswere also given to nine independent service providers across the country to providehealth education and assist in recruitment of Maori and Pacific Island ethnic groups.2.2 Between 1996 and 2000 successive changes to the New Zealand system of healthcare funding meant that the Regional Health Authorities were replaced by theTransitional Health Authority which was replaced by the Health Funding Authoritywhose functions have now been taken over by the Ministry of Health. These changes,often accompanied by changes in key staff, have not contributed to the stability of anew service in its infancy. Under the present organisation the contracts for BSA andfor the National Cervical Screening Programme, (NCSP), are held by the NationalScreening Unit (NSU) within the Public Health Directorate of the Ministry of Health.The NSU not only funds the providers of screening but is also responsible forensuring the quality of BSA and NCSP, for implementing any improvements deemednecessary and for developing both programmes to meet future needs. (See Section 13below).2.3 An Advisory Group for Population-based Screening Programmes advises theMinistry of Health and the NSU on policy issues related to breast and cervical cancerscreening.2.4 There have been three much-publicised failures in cancer screening in NewZealand, two concerning screening for cervical cancer and one concerning Breast7
Page 1 and 2: BREASTSCREEN AOTEAROAAN INDEPENDENT
Page 3 and 4: I SUMMARYSUMMARY AND RECOMMENDATION
Page 5: Independent Monitoring Group10. The
Page 9 and 10: Waikato area and the Bay of Plenty,
Page 11 and 12: 5. POPULATION COVERAGE5.1 Estimates
Page 13 and 14: 5.3.4 Routine Rescreens. The second
Page 15 and 16: Although the register is held withi
Page 17 and 18: of enabling women to reach the scre
Page 19: testing system set up by the Royal
Page 22 and 23: again all Lead Providers have has m
Page 24 and 25: eferral to a surgeon can only be do
Page 26 and 27: 7.6.2 Recommendation The Lead Patho
Page 28 and 29: in any case calculated routinely by
Page 30 and 31: BSA. (A minor easily correctable fa
Page 32: 10. INFORMATION SYSTEMS IN BSA10.6.
Page 37 and 38: 14. RELEVANCE OF THE GISBORNE INQUI
Page 39 and 40: a radiologist working in isolation.

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