MJA: Glasziou & Irwig, Mammographic screening in Australia

Mammographic screening in Australia

Where are we, and where should we be going?

MJA 1997; 167: 516-517

Breast cancer is the commonest cause of cancer death in women in Australia and screening is currently the principal means of reducing this toll. In terms of informing women about screening, the findings of the 1996 National Breast Health Survey, reported in this issue of the Journal by Barratt and colleagues, show that the message is getting through.¹ Most women (89%) had heard of the program, 60% nominated mammography without prompting, and most were aware that women over 50 years should be screened every two years. Further, 87% of women aged 50-59 years reported ever having had a mammogram and half reported having been screened within the national program in the last two years. Mammographic screening is now accessible to most Australian women through one of the 36 screening and assessment services that are part of the national program.

Community values and target age limits are issues for all cancer screening
From a standing start, this is a remarkable achievement in a few years, and a model for what may be required for success in other areas of cancer screening, such as colorectal cancer. There are, however, a number of important policy issues that need to be addressed.
The current combined Commonwealth and State funding for the BreastScreen program is of the order of $80 million per year.² This provides for a 70% uptake of women in the 50-69 years age group plus 40% in the 40-49 years age group. Given the program's good track record, should funds be provided for its improvement or expansion? There are many policy options that can be considered. For example, raising the upper age limit for targeting and reinvitation (currently 69 years), lowering the age limit for targeting (from the current 50 years), reducing the screening interval, or trying to screen more women in the group already targeted. Of these options, the most contentious is the screening of women in the 40-49 years age group.
Recently, additional follow-up of the seven randomised trials that included women aged 40-49 years has suggested a delayed benefit not apparent until after at least seven years. A second National Institutes of Health (NIH) consensus conference on the contentious issue of screening women in this younger age group in January this year concluded there was a statistically significant relative mortality reduction of 16% (95% CI, 2%-28%).³ In absolute terms, if there were about 36 deaths per 10 000 women aged 40-49 years, then regular screening "results in the extension of the lives of 0-10 women".³ The number of deaths prevented by screening women aged 40-49 has recently been estimated to be about one-third that in an equivalent number of 50-69-year-old women.⁴ The consensus panel also pointed out the disadvantages of screening -- false-negative and false-positive mammograms, the psychosocial consequences, and dilemmas such as the detection of ductal carcinomas-in-situ, some of which may never have become invasive. Rather than a blanket recommendation to screen, the consensus panel suggested each woman should decide for herself, but "should have access to the best possible relevant information regarding both benefits and risks, presented in an understandable and useable form". At the subsequent press conference, Dr Richard Klausner, the Director of the National Cancer Institute, stated that he was shocked by the report and announced that it would be reviewed by the National Cancer Advisory Board. Following a United States Senate hearing, the National Cancer Advisory Board voted 17 to one in favour of screening women aged 40-49 years every one to two years. Interestingly, in all this heated debate, no one asked the affected women how they felt about the benefit-harm tradeoff.

At a recent Australian National Breast Cancer Centre consensus meeting about screening in 40-49-year-old women, Jill Cockburn (Head, Discipline of Behavioural Science in Relation to Medicine, University of Newcastle, NSW) reported national survey results that showed that most women in this age group felt that the benefits outweighed the risks. However, most also felt they should be given all the information and allowed to make up their own minds rather than there being a blanket recommendation to screen. Enthusiasm for screening also declined when information about the balance between the benefits and disadvantages was given. Similar declines in enthusiasm following receipt of appropriate information have been shown for prostate cancer screening⁵ and for cholesterol reduction in asymptomatic people.⁶ In an era of evidence-based practice and tight resources, involving target groups in screening decisions will be vital for formulating rational and acceptable policy.

Community values and target age limits are issues for all cancer screening. In general, cancer incidence and mortality continue to rise with age, suggesting we should target older people. However, life expectancy also decreases with age, and the likelihood of dying of other causes before the cancer becomes troublesome increases. Combining the mortality and life expectancy information allows us to calculate age-specific "potential years of life lost"; this is shown for breast cancer in the Figure. There is a steady rise with age, reaching a peak late in the fifth decade, followed by a slow decline. This confirms the appropriateness of the age interval initially chosen by the BreastScreen program, but raises the difficult issue of where we should now draw the line on either side of the peak. This will depend on the balance of benefits and harms as we move away from the peak, and will require input from a representative community sample about their value judgements on the net worth of screening. If this did not give a clear-cut decision, individual informed consent should be required. With such community value judgements and an awareness of the costs, we could make a rational decision about how to best allocate Australia's resources for screening.
Paul P Glasziou
Reader in Clinical Epidemiology, University of Queensland
Les M Irwig
Associate Professor of Epidemiology, University of Sydney
Barratt AL, Cockburn J, Redman S, Paul C, Perkins J. Mammographic screening: results from the 1996 National Breast Health Survey. Med J Aust 1997; 167: 521-524.
Dorsch M. A perspective on the BreastScreen Australia experience. First National Breast Screening Conference; 1997 Aug 21-23; Canberra. Canberra: Commonwealth Department of Human Services and Health, 1997.
National Institutes of Health Consensus Development Panel. National Institutes of Health Consensus Development Conference Statement: breast cancer screening for women aged 40-49, January 21-23, 1997. J Natl Cancer Inst 1997; 89: 1015-1026.
Irwig L, Glasziou PP, Barratt A, Salkeld G. Review of the evidence about the value of mammographic screening in 40-49-year-old women. Sydney: NHMRC National Breast Cancer Centre, 1997.
Flood AB, Wennberg JE, Nease RF, et al. The importance of patient preference in the decision to screen for prostate cancer. J Gen Intern Med 1996; 11: 342-349.
Reed WW, Herbers JE, Noel GL. Cholesterol-lowering therapy: what patients expect in return. J Gen Intern Med 1993; 8: 591-596.
Kricker A, Jelfs P. Breast cancer in Australian women 1921-1994. Canberra: Australian Institute of Health and Welfare, 1996. (Cancer Series No. 6.)

The Medical Journal of Australia eMJA

Readers may print a single copy for personal use. No further reproduction or distribution of the articles should proceed without the permission of the publisher. For permission, contact the Australasian Medical Publishing Company
Journalists are welcome to write news stories based on what they read here, but should acknowledge their source as "an article published on the Internet by The Medical Journal of Australia <http://www.mja.com.au/>".


	Breast cancer is the commonest cause of cancer death in women in Australia and screening is currently the principal means of reducing this toll. In terms of informing women about screening, the findings of the 1996 National Breast Health Survey, reported in this issue of the Journal by Barratt and colleagues, show that the message is getting through.¹ Most women (89%) had heard of the program, 60% nominated mammography without prompting, and most were aware that women over 50 years should be screened every two years. Further, 87% of women aged 50-59 years reported ever having had a mammogram and half reported having been screened within the national program in the last two years. Mammographic screening is now accessible to most Australian women through one of the 36 screening and assessment services that are part of the national program.
Community values and target age limits are issues for all cancer screening	From a standing start, this is a remarkable achievement in a few years, and a model for what may be required for success in other areas of cancer screening, such as colorectal cancer. There are, however, a number of important policy issues that need to be addressed. The current combined Commonwealth and State funding for the BreastScreen program is of the order of $80 million per year.² This provides for a 70% uptake of women in the 50-69 years age group plus 40% in the 40-49 years age group. Given the program's good track record, should funds be provided for its improvement or expansion? There are many policy options that can be considered. For example, raising the upper age limit for targeting and reinvitation (currently 69 years), lowering the age limit for targeting (from the current 50 years), reducing the screening interval, or trying to screen more women in the group already targeted. Of these options, the most contentious is the screening of women in the 40-49 years age group. Recently, additional follow-up of the seven randomised trials that included women aged 40-49 years has suggested a delayed benefit not apparent until after at least seven years. A second National Institutes of Health (NIH) consensus conference on the contentious issue of screening women in this younger age group in January this year concluded there was a statistically significant relative mortality reduction of 16% (95% CI, 2%-28%).³ In absolute terms, if there were about 36 deaths per 10 000 women aged 40-49 years, then regular screening "results in the extension of the lives of 0-10 women".³ The number of deaths prevented by screening women aged 40-49 has recently been estimated to be about one-third that in an equivalent number of 50-69-year-old women.⁴ The consensus panel also pointed out the disadvantages of screening -- false-negative and false-positive mammograms, the psychosocial consequences, and dilemmas such as the detection of ductal carcinomas-in-situ, some of which may never have become invasive. Rather than a blanket recommendation to screen, the consensus panel suggested each woman should decide for herself, but "should have access to the best possible relevant information regarding both benefits and risks, presented in an understandable and useable form". At the subsequent press conference, Dr Richard Klausner, the Director of the National Cancer Institute, stated that he was shocked by the report and announced that it would be reviewed by the National Cancer Advisory Board. Following a United States Senate hearing, the National Cancer Advisory Board voted 17 to one in favour of screening women aged 40-49 years every one to two years. Interestingly, in all this heated debate, no one asked the affected women how they felt about the benefit-harm tradeoff.
	At a recent Australian National Breast Cancer Centre consensus meeting about screening in 40-49-year-old women, Jill Cockburn (Head, Discipline of Behavioural Science in Relation to Medicine, University of Newcastle, NSW) reported national survey results that showed that most women in this age group felt that the benefits outweighed the risks. However, most also felt they should be given all the information and allowed to make up their own minds rather than there being a blanket recommendation to screen. Enthusiasm for screening also declined when information about the balance between the benefits and disadvantages was given. Similar declines in enthusiasm following receipt of appropriate information have been shown for prostate cancer screening⁵ and for cholesterol reduction in asymptomatic people.⁶ In an era of evidence-based practice and tight resources, involving target groups in screening decisions will be vital for formulating rational and acceptable policy. Community values and target age limits are issues for all cancer screening. In general, cancer incidence and mortality continue to rise with age, suggesting we should target older people. However, life expectancy also decreases with age, and the likelihood of dying of other causes before the cancer becomes troublesome increases. Combining the mortality and life expectancy information allows us to calculate age-specific "potential years of life lost"; this is shown for breast cancer in the Figure. There is a steady rise with age, reaching a peak late in the fifth decade, followed by a slow decline. This confirms the appropriateness of the age interval initially chosen by the BreastScreen program, but raises the difficult issue of where we should now draw the line on either side of the peak. This will depend on the balance of benefits and harms as we move away from the peak, and will require input from a representative community sample about their value judgements on the net worth of screening. If this did not give a clear-cut decision, individual informed consent should be required. With such community value judgements and an awareness of the costs, we could make a rational decision about how to best allocate Australia's resources for screening. Paul P Glasziou Reader in Clinical Epidemiology, University of Queensland Les M Irwig Associate Professor of Epidemiology, University of Sydney Barratt AL, Cockburn J, Redman S, Paul C, Perkins J. Mammographic screening: results from the 1996 National Breast Health Survey. Med J Aust 1997; 167: 521-524. Dorsch M. A perspective on the BreastScreen Australia experience. First National Breast Screening Conference; 1997 Aug 21-23; Canberra. Canberra: Commonwealth Department of Human Services and Health, 1997. National Institutes of Health Consensus Development Panel. National Institutes of Health Consensus Development Conference Statement: breast cancer screening for women aged 40-49, January 21-23, 1997. J Natl Cancer Inst 1997; 89: 1015-1026. Irwig L, Glasziou PP, Barratt A, Salkeld G. Review of the evidence about the value of mammographic screening in 40-49-year-old women. Sydney: NHMRC National Breast Cancer Centre, 1997. Flood AB, Wennberg JE, Nease RF, et al. The importance of patient preference in the decision to screen for prostate cancer. J Gen Intern Med 1996; 11: 342-349. Reed WW, Herbers JE, Noel GL. Cholesterol-lowering therapy: what patients expect in return. J Gen Intern Med 1993; 8: 591-596. Kricker A, Jelfs P. Breast cancer in Australian women 1921-1994. Canberra: Australian Institute of Health and Welfare, 1996. (Cancer Series No. 6.)